Can the Anomalans send someone to Malachite with a translator earpiece-and-speaker setup to free up optimization-power for other criteria or would hearing everything through a text-to-speech program be too annoying? 

That's totally fine, and they can provide corpuses of Lune (Eluin's primary language), Niqait (Niqal's), and Lirami (Tisa's) for the machine translation.

Text-to-speech exists and while it's primarily an accommodation for the blind nobody in Malachitin will blink about an elf using it because they're better at spoken languages than written. 

A sealed sphere cracks and an old man, older than 60, older than almost anyone lets themselves get without going into suspension, gingerly climbs out of it, assisted by a servo exoskeleton.

It's painful to abandon all the sunk costs that Civilization paid, but they are sunk.  They're already interacting with multiple unscreened other pasts.  It's clear both what needs to be done, and that it needs to be done right now.

The dath ilani around look openly shocked, not too shocked, the prediction markets guessed this might happen, but it's still pretty shocking.

The old man walks past, exoskeleton-assisted, to where a Green and an Anomalan are talking to a dath ilani.

"The problem," he says in Baseline, "is that their, our, Civilization, was founded around a premise long ago, that there wasn't any such thing as a Pharonian or a Martinian child, just children, and then for unrelated other reasons they had to screen off their past, and also did some heritage optimization, and now they don't know what it's like to think differently.  They aren't going to react the tiniest bit differently to the Bobbiverse killing six-year-olds in the Bobbiverse, and the Bobbiverse or a rogue dath ilani faction killing six-year-olds in dath ilan.  They don't think that cultures can own children, and while that's correct from my own ethical standpoint and also I'm guessing from yours, they also don't know what it's like to think differently or remember a time in their history when that wasn't true.  They no longer have a record of what goes wrong when two different cultures interact, and their prediction markets are being too optimistic about it or were as of five seconds ago."

He then waits for the dath ilani there to translate this into written form, where it can be passed to the Anomalan and Green without being intercepted by the elf.

"- screen off their past?" says Shrey, alarmed, "what does that mean - also of course the six year olds aren't necessarily any more different than particularly diverged breeds of dogs or something but the strategic and diplomatic constraints differ enormously - why were you in a hamster ball -"

"To try to protect the past from everywhere else.  If you haven't worked it out yourselves then I probably shouldn't say more.  It didn't work, anyways."

"The people here don't run Governance.  Civilization runs Civilization.  They're going to run conditional policy prediction markets and vote on which of those outcomes they want to see and the number of dead six-year-olds summed across all worlds is going to loom very large as a factor in that vote, and they're also going to ignore any additional dead six-year-olds produced in an attempt to intentionally influence that vote while being very shocked and sad that anybody would do that in reality instead of a counterfactual."

"We predict that any violent responses will not be attempts to influence your decisions, but the result of a direct incentive to prevent interference. As such it will be reasonable to take them into account, and possible to prevent them with diplomatic delicacy."

"It would take a lot of work to get Civilization to tear itself into two pieces, but presenting them with a choice between being the only defecting world in a larger system of friendly cooperators, on the one hand, and letting huge numbers of six-year-olds die and be lost and possibly scattered, on the other, would plausibly do it.  On the plus side, they will be very eager to go along with it if you can present them with any option whatsoever which is not that."

"Well, you could offer to take the excess children as refugees, if we can't figure out how to get them to have the desired number in the first place," says Shrey. "Six-year-olds aren't very big, you could plausibly set up some kind of bucket brigade arrangement."

"Your past was kinder than our true past if you expect that to work," says the old man.  "We could pay them to cryopreserve the children, at that rate; they said they have the technology.  People do not do such things because they have calculated it as the best way to achieve their desires, of all the ways considered, but because it is part of their image of who they are."

"Then we'll find a way to convince them that they're the sort of people who switch to better solutions as they become available. One of us--probably me or Shrey--should talk to a Bobbiverse representative alone."

"Our ad has gotten a good candidate," Shrey says, checking her handheld, "for a Bobbiverse ambassador, and she's bringing flowers. It's possible they just have a cultural identity around specifically killing the kids but it could easily be something else, if they just feel it's eugenically necessary then shipping them out at your expense would do just as well, if they're missing birth control because they're too busy inventing incredibly fabulous outfits likewise."

"Excellent, we've mostly gotten offers from historians who want to study them. We have totally nonviolent eugenics and can write up a case for its effectiveness."

"We have what's called on-sight-abortion where a defect that was for whatever reason not detected prenatally is identified at birth, and then there's infanticide if the parents prefer, but in brand new infants, not six-year-olds."

"We have that and also an exception for euthanasia if the baby is guaranteed to die painfully before the age of three. Though we've mostly eradicated the genes for that class of problem so it almost never comes up."

The elf is annoyed to have been underhandedly excluded from the conversation instead of just asked politely.  The dath ilani are Very Rude.  The elf does not actually say this, because she understands the difference between times when acting on your feelings immediately is productive in interpersonal situations and times when it is not, UNLIKE THE DATH ILANI

"Are you sure that what we're seeing is reality?" says the other dath ilani, in Anomalan; it doesn't seem helpful to hide this from the elf.  "Green and Firstplanet look like plausible, stable societies that could have arisen naturally.  The rest of these, with the possible exception of Elfland - feel confusing in the unnatural way that children learn to identify with adults constructing elaborate fake scenarios around them, once they realize that's what happened.  Or at least, that sure is how it feels to me.  These presentations are meant to look like bait, or tests of character - societies looking weak with planets easy to seize for resources, weak and in need of help, insane and committing an escalating series of atrocities that other societies might be tempted to intervene in.  We may be the only ones here who are foolish enough to present themselves as we are, instead of presenting an elaborate facade designed to extract maximal information of interest from any other worlds foolish enough not to expect that."

"You think they decided to send actors to claim to have disastrous problems back home as bait? That would be a very weird thing to do in real life," says Shrey. "They're clearly very weird, but that's a very specific way you're proposing that several of the delegations are being weird, although I guess maybe you think they coordinated with each other and not with us?"

"They wouldn't need to coordinate if it happens to be what most hominid-derived societies decide on, much as they decide to wear clothing of some form, with ourselves being the odd nudists out, unconcealed."

"We have corpuses of their literature, and they didn't specify that they were only to be used for translation. We can go through them for references to the murders. It could have all been faked while we were setting up the biosafety protocols but it would have taken thousands* of people, or for them to know about contact in advance."

*Literally '4096s of people'.

"Technology that understands text well enough to translate it has an obvious higher rung that understands text well enough to modify or generate it."  Everyone on this mission knows about machine learning.

"If it's a strategy a lot of worlds converge on I would also expect it to have happened at least a few times among cultures in our history," says Shrey, "if not with the text generation part, since ours isn't good enough to write novels even now, but still. You might be particularly impaired at reasoning from that sort of thing because one person in a hamster ball can't really be an expert on all history, but my consultants aren't turning anything up."

"Our machine text generation isn't anywhere near that good, but theirs could be. And it's not a thing that's happened in our history either. Also, they didn't make excuses about not wanting an ambassador. We could try to accelerate that; if it's all a facade they'll have to start pushing back on that at some point."

“If we end up getting absolutely nothing out of this then I suppose we’ll be mildly put out,” says the Bobbiversian in vantablack, to the keeper, several minutes ago. “Oh well. We-are-no-longer-talking-to-you-in-particular-go-away.”

A separate Bobbiversian notes to the Anomaland delegation that they do have lots of sterilization surgeries and drugs and also that lots of them are variably legal and also that all of them have weird side effects, do they have any without weird side effects - it transpires that they never invented rubber condoms, if those come up - and the Bobbiversian in vantablack is more than willing to answer that elf’s questions! Children are raised in creches because they’re a convenient institutional format for keeping them somewhat separated from society; in the past they used to just wander around entire villages or households being raised collectively but that’s a big disease risk, right, and it’s not great for anyone getting anything done, only some cities allow creches in at all.

Men produce the most children per, and tall-purple-flower-women produce the least, but on a statistical level the children of men are much more likely to end up being murdered; they’re somewhat above replacement in total and would be much more above replacement if not for all of the murder. Lots of countries have some kind of incentive structure in place for having children; it’s usually just ‘here, have this amount of currency’. The murder of babies and small children is in fact somewhat controversial but it’s very hard to scale it back without making people concerned that they’re going to lose access to their UBIs, or that they’re going to overrun the planet, or that the crime rate is going to explode from all the men not being murdered in childhood, and it’s hard to scale back the birth rate without people getting concerned that they’re going to shrink down into nothing, and it’s very hard to coordinate on scaling back infanticide quotas and the birth rate at the same time.

The bobbiverse corpus they sent over seems to contain fiction and apparent-nonfiction describing thousands upon thousands of different societies, most of them extremely weird or magical or horrifying or sexual or all four, and mostly declines to mention children when they aren’t being worked into fantasy worldbuilding. Even their textbooks seem to come from countless different worlds, although usually only as a medium for discussing real chemistry or physics or similar.

"I think I credit their true existence more than the prediction markets do, but I'm also not as smart as modern kids," says the elder.  "But in our history there have been instances of creating false villages to deceive foreign ambassadors about the state of a country."

The other dath ilani nods, and translates.  "Yes.  It may not seem like an obvious strategy to you, but it does to us.  Maybe it didn't happen in your own history, but it did in ours.  So it's a thing which humans may do - maybe not your exact kind of human, usually, but some kinds of human - and now we've learned that they do it even when they are resourced at far lower levels than an equiv-tech civilization.  This is also not necessarily their own true first contact; they may have had time to prepare their strategies."

The Keeper neither nods nor gives any form of other acknowledgement to the Bobbiversian, simply turns to go.  This outcome was foreseen, in a certain branch of possible reality, and considered necessary within it.  Dath ilan isn't going to send an infiltration mission into the Bobbiverse while the not-gaslighting!Bobbiverse could possibly be under the impression that dath ilan is their cooperative friend.

Orlan says to Shrey and the historian, "Assuming they're telling the truth, we can probably get somewhere by making contact with one of the factions that wants to scale back on the birth rate and the infanticide in tandem and offer them lots of nice things and help them with whatever bottlenecks are stopping them from winning, and then it will be somewhat less like we're trying to impose our own views instead of just being better friends with the faction that's more like us plus it being useful to be our friends."