It was a smaller more densely defended Wound at the time! Here's a book about the emplacement of the Wardstones which incidentally has some facts about what it was like before that. This librarian thinks succubus infiltration is scarier than teleportation. Teleportation just means a monster can show up and maybe torture you and then kill you and then you're dead, succubus infiltration can with long enough to work make people Evil and stuff.

...demons have armies. A teleporting army can go wheverever your army isn't and destroy your cities and industry and farms until there's nothing left. It can attack any nation in the world that happens to be weak or beneficial to pillage. Whenever presented with a problem, it can teleport away. It doesn't need a supply trail because it can teleport supplies and also rob yours. It can divide in ten or a hundred pieces and reconvene whenever it needs to. That's an army that can win any war. Certainly it can win a war which, with the existence of the Wardstones, is still a bloody stalemate seventy years later! The size of the Worldwound and the defenses around it don't matter if the demons can just teleport past them!

What does the book have to say about this?

The book seems to think that demons just don't spend extended periods of time organized into armies and frequently kill each other.

That is not the impression she got from the history of the latest (fourth) war/crusade? Admittedly she only skimmed it, but she's pretty sure demon armies featured in it!

...no, this makes sense. If the books are correct (and complete) the demons only organized into armies much later, presumably in response to the Wardstone line which blocked individuals or small groups. This is plausible; if you don't have that sort of organization already it's not going to spring up overnight, or possibly ever. 

The demons seem to be like inmates in a prison. When the wall was broken they all wanted to escape, but getting criminals who spent the last eternity fighting each other to cooperate is presumably very hard. The defenders ought to focus on whatever enables the demons to form armies; organizations can be decapitated, organizational knowledge forgotten. If a demon army does make it past the Wardstone line to where they can teleport, or if the Wardstones break down, they'll probably disperse into small groups again and be impossible to confront as an army, even aside from all the teleporting.

A horde of criminal mages randomly spreading around the world is in many respects scarier than an army. An army has coordination which can be disrupted; commanders who can be negotiated with; goals which can be fulfilled or denied. An army wants, on some level, to stop fighting for at least some of the time, to have and enjoy victory in a way that includes peace, to demobilize most of its soldiers. A prison break has people who just want to live in peace and some who are serial murderers, and the latter don't have a win condition after which they'll stop. As individuals they can be stopped by ordinary police or the home guard, but you'd need police on the scale of a fully mobilized army to catch them all - and because they don't have specific goals, they'll teleport whereever your police aren't.

Something is still wrong with this picture. It implies individual demons freely teleported out of Sarkoris into the rest of the world for thirty years. Wouldn't all the demons have left the Abyss? How many demons are there, anyway? 

Does the book or the librarian have any explanation for this?

"Oh, there are an infinite number of demons. - not here, the Wound is a meaningful chokepoint, but in the Abyss."

"...so what was stopping effectively infinite demons from coming through the Wound and teleporting away during the thirty years before the Wardstones?"

"The Abyss is also spatially infinite so most of them aren't near the Wound and the ones who were often fought each other before coming through."

Huh. So the Wound happened to open to a relatively empty area in the Abyss, and it took a long time before many demons gathered near it. Even though they can travel at the speed of teleport, and so can news of the Wound inside the Abyss. ...unless every demon who heard about it immediately tried to escape through it instead of spreading the news?

The librarian presumably doesn't know the answers. It doesn't much matter in the current strategic situation, but the obvious way to improve it is to move in the Wardstone line and that will return the Wound to its original 'small chokepoint' state...

Tanya shouldn't get lost in trying to analyse a distant war she's not fighting in on the basis of extremely patchy information. If she actually goes to the Worldwound she'll have a lot more questions, and a lot less willingness to accept vague answers. As much as she doesn't want to sign up for another war, she wants to sign up for another losing war even less. She hopes very much that it won't come to that.

She thanks the librarian and puts the books back.

"I'd like you along when we head back to the inn on the offchance that the proprietor will object to me looking different than I did when we booked the room."

"Of course." Tanya wasn't particularly planning on going anywhere else; she can have dinner at the inn itself.

Niss continues to really enjoy eating plants and dairy products!

And then they can turn in.

Nobody should be condemned to a diet of mushrooms. This is probably a human sapient right or something.

(Tanya is by now mostly through her caffeine (and chocolate) withdrawal and is honestly a bit afraid of checking if they're on sale anywhere in the city. What if they are, but they're very expensive. What if she's told they exist halfway around the world. Her priorities would be completely warped! She's trying to hold on until she at least has an independent income source, and maybe a way out of Hell.)

Ancestral Regression lasts until the same time the next morning but rather than risk turning purple in the middle of the street Niss stays in till it's happened, and then heads for the library to read more books; she will meet Tanya at the Abadarans' when the noon bells ring.

Which leaves Tanya with a few hours free and unsure what to do. She hasn't found any very promising books in the library. She could probably ask the Abadarans more questions, get their perspective on the Worldwound or their project of quantifying charity donations for the remission of sins, but perversely if she shows up and the investor happens to have an hour free she'll need to talk to him without Belmarniss - no, that's silly, she can always fly quickly to the library. Tanya can stand a little social embarrassment due to poor scheduling.

This won't fill several hours, though. She can find another Shelynite to talk to, maybe get a different perspective. Or - in Rome, do as the Romans do? (Famously religious, the Romans.) Tanya can bow to the inevitable and check if there are any more churches in town and what they have to say for themselves, since apparently churches organize a bunch of social and financial activity around here.

Do any other probable-churches stand out?

This is a substantial city with lots of churches! Some of them are duplicates - there are for example several smaller Pharasmin temples in addition to the big chonky one, and branches of the bank of Abadar. There's Iomedaeans, a few branches of them. She may have more difficulty recognizing the church of Cayden Cailean, since it's pulling double duty as a tavern, or the church of Desna, which is pretty small and unstaffed, or the well-appointed but outdoor shrine to Gozreh in the port, or the church of Gorum doubling as a military recruitment office.

It's just as well that she doesn't recognize those on sight. Tanya might a very hard time respecting Taldor and its laws if she learned their army belonged to a church!

Iomedae is, um... she has an origin myth as a human who became a god after touching a magic rock and being judged good and lawful by Pharasma. She used to follow Aroden (or be subordinate in the same pantheon?), so after his death some Arodenites converted to her religion. She empowers paladins, a martial kind of cleric who uses swords as well as spells. Paladins can detect evil at will; they're not allowed to assault you about it (because that's illegal) but they might follow you in the street telling everyone loudly to shun you or something.

Pharasma is of course the judgy god. ...goddess. Her clergy ought to be good at telling Tanya how to get in her good graces. It will probably involve a lot of preaching and disapproval first. Still, they might be better than the paladins? Honestly, neither option appeals. She'll talk to them - after she exhausts her other options.

Tanya ends up going to the temple of Shelyn again. They might not be able to help her, but they at least seemed like reasonable well-adjusted people, following an inoffensive religion which is sensibly staying in its religious/cultural niche instead of taking over functions like running banks or libraries. (At least, the one possibly-lay follower she talked to seemed reasonable enough.) She'll try to strike up a conversation with someone else this time.

It's the morning and there are services ongoing! There's a hymn in progress wafting out through the doors! She can find standing room in the back.

Maybe it will end soon. What is it about?

Colors! They are beautiful. Praise be unto them and to Shelyn and the light by which we see and so on.

Praise be unto... colors? Not the god who made them or made us to see them or something? What do colors want with being offered praise?

Whatever, it's a foreign language and culture and neither songs nor religion are obliged to make any sense. It might be one of those songs that's nicer to listen to if you don't understand it, but she can't turn the translation spell off and on like that.

After they are done singing about colors a priestess goes up and delivers a sermon about how it is nice for people to have nice things even if they are not nice people, so long as they do not in so having deprive anyone else of anything nice. The Isle of the Penitent has every soul who would not natively take to Nirvana right away but who has been snatched from the courts of the Judge by cunning lawyer-agathions finding and arguing for the good latent in their heart, and the simple joys of things like color and peace are theirs, there, until they are ready to join the greater choir.

The more things change, the more things stay the same. They have prosocial lawyers, but the ultimate reward is still being stuck in a choir everlastingly praising god the concept of colors.

...if this doesn't end soon she'll leave quietly.

From her arrival there's about thirty minutes left in the entire service (it ends on another song, this one is about all the animal-people there are in Nirvana).

Nirvana is for everyone! Even the spider-men and the mushroom-women!

The phrase "Nirvana is for everyone" appears in the song but it does actually seem to mostly focus on how you won't be a human any more there and might be able to fly on eagle wings or something.