It's a creative idea but no.  In lieu of explaining that one exact detail, Almys just takes out his current registration and shows it to her: it's high-quality paper that seems obviously magical, it mentions his birthplace city off in another kingdom, it says where he's currently permitted to be (Midvale County, no mention of a particular city), and, yes, it includes his date of birth.  Another page has photos of him as both a man and a woman, and his fingerprints and toeprints.

"I am again very impressed at how tyrannical your society is. What goes wrong if you show up with a newborn baby and try to acquire such a paper for said baby?"

"I... don't think anybody would ask too many questions about that?  They'd just reg the baby."

"And dye the baby's head with a sort of very faint purple magical dye that doesn't fade for a month."

"And then they check all adults for magical purple dye and can see through an illusion covering it?"

"No, they notice that the reg papers are for a one-day-old baby and this seems to be an adult, and then they have all kinds of questions... I guess we could bank on them not bothering to check the date, for some things."

Almys will tap specifically the part of his registration papers that show the date, now that his brain has caught up with the concept that possibly date formats differ between universes and the Summoned Hero did not immediately recognize this as a date-of-birth code.

Indeed, she has no idea how they count years here or what that date means. "Is there an error rate with the documents, such that it could be plausible the date was wrong? Though I guess being a baby whenever we move counties is also not that inconvenient."

"The papers are produced by artifact, so no, it wouldn't be all that plausible that this was an error nobody had previously noticed for however many years..."

"Actually I should back up a step.  I really have to notice my confusion harder when dealing with you.  One doesn't see through an illusion; an illusion is just light.  You can notice a problem with an illusion or you can notice the magic underneath an illusion; you can't see through them because the light is just... there."

" - our kind of illusions you can succeed at disbelieving and then they're partially transparent, like the part of the work that was being done by your mind isn't being done anymore."

"Thaaaat sure sounds like a completely different kind of illusion that would potentially defeat all sorts of standard countermeasures, and maybe not some other kinds of standard countermeasures, and I am unfortunately not at all a specialist in this."

"Anyways, we can get you across county lines by flying invisibly over them - so far as I know - and I can cross them legally and get my regs updated by doing so.  We can newborn-infant you, reg you, and I can cross county lines with you that way, including by teleport though that costs money to do over a distance.  Your adult self wouldn't be registered once you got there, but you're not any more registered here in Midvale.  I think it's safe to say that we can jump counties if we've got a reason."

"If the costs aren't too high I probably want to do it even without much reason, because if anyone's started to put together any clues I want to be gone before they can gather more of them. Also it might be nice to be in a location where I can go out flying when I take a break from trying to learn channeling. And then at some point we'll want a secure base of operations, though I think I'll need to get better at magic first.

....how do Summoned Heroes usually do any adventuring, if they need adventuring to level, and you can't adventure without a guild registration, and you can't get a guild registration without a birth-issued magically-secured identity document, and nowhere in the world can you get one of those except as a newborn? Or is the idea that it's meant to be impossible for Summoned Heroes to get powerful without being immediately detected as such?"

"Oh, the governments sure do try to set it up that way.  And yet somehow - though there are not, for obvious reasons, any details we are allowed to know - the story does not usually involve the Summoning Hero sadly giving up and identifying themselves to the government during their first few days."

"Very competent tyrannies are, while of course I approve in principle, not systems you want to identify you as valuable and/or a threat! I think it's worth getting me a baby registration, if only because the date anomaly will seem less weird to anyone who does notice it once the date's a while in the past."

"Actually I think that going around in your twenties with a valid reg magically bound to you, that was issued one month ago to a newborn baby, with photos attached of that baby, will in fact continue to raise eyebrows just as much as the same reg issued to a day-old baby."

"We can get you a fake reg, at some point.  We just need to navigate the criminal social world to find out where there's a bribable high official and then spend way more money than I currently have."

"But to be explicit, I think that I basically know how to move us across counties if you give the order.  Say that it'll cost about a month's of living expenses and I have something like three months of savings left; as an Adventurer you mostly want to spend money on magic items as you earn money, so you can increase your future income, rather than save that money.  Being able to snowball that is probably the main reason why governments let Adventurers keep any significant amount of their dungeon earnings at all instead of taxing the whole thing."

"All right. Let's say not yet, and default to once I've figured out how to fix the Acid knife - of which the hard part is going to be channeling Acid, I think, I need to see how the blade creates the spell-structure to guess how to put it back together. But if anything seems off, then we can leave sooner. 

...why is there an adventurer's guild at all, why not let anyone who wants to adventure do that? Are there, you know, normal non-artificial-dungeon adventures where there are monsters in places and people need help with them?"

"There's more people who want to level than there are real fights to level them.  So the governments control the dungeons, and the amount of taxes and qualification tests and Adventurer's Guild bullshit and random quests that city lords throw at you and mandatory service with long hours, plus all of the other pain and inconvenience, rises to a level where the demand to be an Adventurer is low enough to meet the number of dungeons.  If there was excess demand and more people wanting to be Adventurers than there are dungeons, the Guild and the governments would have room to make things worse again, so they would, because that's how people are if nothing is stopping them."

"And, I mean, sure, there's normal monsters too, but nobody'd hire anything but an appropriately ranked Guild team because anybody else you send is just going to die, right, and if they don't you'll get in trouble with the Guild about it."

"That's clever," says Carissa in the tone of someone who thinks she should approve wholeheartedly and doesn't exactly. "....but we could go fight normal monsters to level? If that's what's needed before I pick up Tier-2 channeling?"

"That... possibly works.  We'd need to find some smaller town with recurring monster problems, small enough that they don't have their own Guild, and they will want to see our papers but they're not going to see through any illusion magic that isn't based on Light affinity."

"That sounds good. I want to keep trying a little longer at channeling, in case it just needs time, but it seems entirely possible I actually do need to level, and in that case a small town where it'll take a long time and have less immediately catastrophic consequences for people to notice anything unusual seems ideal. 

Are we near, uh, the fire? Are people able to go take a look at the fire?"

It takes him a second to work out that she means the Fire, as in the one consuming the planet, since she didn't capitalize the word when she said it.  She probably meant that earlier, too, when she was talking about 'putting out the fire'... he should've noted explicitly and out loud when he was confused before about 'which fire'.

"No, we're pretty far from it.  Not literally as far as it gets, but, like, two-thirds as far away as you can get."

“I guess it can wait.”

"Neither of us have anything like the leveled Skills to go inside it anyways, unless you have some very extreme protection from Fire in your Uncreation magic."

“Only the normal amount of resistance to fire . I guess I could start casting it on myself regularly so the universe gets used to me having it. My kind of magic crafting can do immunity to fire, but not easily.”

"Should we be trying to get you fifty pounds of spellsilver before we go?  I don't expect a smaller town to have its own Transmuter Device."

“Then yes, probably. If they’ve produced spellsilver but don’t know it had to be stored in oil, it’ll have a grimy grey exterior and be beautifully silver on the inside.”

"I don't see why they'd produce spellsilver and store it if they didn't have an order for it.  Unless they've got samples of everything on hand, and now that I'm thinking about it, I'm not sure why they actually would... do you know whether there's only one pure metal that grimes in air like that?  Do you know if it's good for anything else besides Uncreative crafting?"