Then Tanya will fly after her!

Does anything else stand out about this city, given that she forgot to ask Belmarniss how much it would be acceptable to light it up and so is being conservative about not drawing attention or offending people?

If she looks she can see evidence of the sign language - those kids whose corresponding grownups are having a loud conversation are signing at each other, and those people who are leaning out of their windows on either side of this street-tunnel-cave-thing are, and those people who have a bunch of tiny people in their shop working on sewing stuff are doing it. Nobody using light appears to be exhibiting particular caution about where it may fall. They have leather, and they have silk, and there is a very little fur around, and there's not much sign of cotton or linen or wool. The smoke from the cooking fires at the restaurants is not obviously accumulating, nor can it be easily smelled from a few paces away. (The food can be smelled.)

Magic ventilation? Magic cooking fires? Who knows, but it's heartening that all the little things she notices are features of perfectly ordinary civilian life and not, say, fights breaking out or legions drilling or people fleeing a T-rex.

(Tanya does Not Understand the underground ecology and will not attempt to decipher it without a proper explanation.)

Eventually Belmarniss picks a food place! She does some talking to the proprietor and gets two bowls of mushrooms in a goulash-esque mixed-texture preparation. Offers one to Tanya.

Tanya will attempt to eat it! Hopefully whatever this is is good for Tanya, because she is evidently not getting out of eating local food. If there are going to be any issues it's better to identify them now.

It's mushrooms! Whether she likes it will depend a whole heck of a lot on whether she likes mushrooms.

Tanya has nothing against mushrooms! Maybe she'd change her mind if she had to eat them every day, but even if it were particularly unpleasant for some reason she's a soldier and she is capable of eating that which must be eaten.

They're pretty filling for mushrooms. There's maybe a little lard in there to round it out.

After they have eaten and turned over their bowls they can proceed thisaway!

Tanya will dutifully follow.

She has a lot to think about but her thoughts are running in circles. She's trusting Belmarniss, she has no information except through her and she has no obvious avenue to get such information. It's very suspicious that the first person she landed on in a random cave wanted to leave this cave and needed something Tanya might be able to provide, and had a language spell ready (and their teacher had another), and didn't take any time to think it over or talk to anyone before agreeing to this plan, and trusted Tanya for her part in it. After telling her other people in this city cannot be trusted and some of them are paper-thieves.

...alright, but what else is she going to do, talk to random people? Hope someone else has translation magic and wants to talk to her and tells her a contradictory story and she decides to trust them and not Belmarniss? Find many such people to see which opinion is more common? Go off on her own to try to reach the surface, which she only knows about from Belmarniss, and where she won't be able to communicate either, on what is supposed to be a week-long trip with two days' rations?

Tanya has a sinking feeling that she's not doing the right thing and "cooperate the first time" is not a sufficient reason to go ahead, and she cannot figure out what to do instead.

Well, is she going to interrupt Belmarniss booking her a room in a Cave Hotel?

Of course not! She doesn't even know that's what Belmarniss is doing! 

She might be able to guess from the hotelness of the cave! And the part where Belmarniss leads her to a room with a door that locks and gives her a key and the room inside has a hammock and a chamber pot and a little bench-seat-thing carved into the wall.

The hotelness was not very obvious before being shown the room!

"In how many hours do you plan to come back?" She can show her the clock-illusion again, counting off seconds and minutes which can be multiplied out to hours.

"Ten."

"Is anyone else supposed to come in besides you or should I refuse to open the door?"

They covered: "Yes-or-no question."

They also covered first-or-second! ...no, she's right, the answer to each part could be yes or not separately, even if that's unlikely.

"Sorry. Is anyone else supposed to ask to come in?"

Belmarniss hovers her hand at waist height and then points at the chamber pot.

"One of those short people will come to replace the chamber pot. Will they have their own key?"

Headshake. She puppet-ifies her hovered low hand and has it chirp a Drow word, then mimes knocking.

Tanya writes down the word. "If I do not answer will they go away?"

Nod.

"Alright. I'm not sure to what extent we are trusting the hotel for security. If I'm woken by someone opening the door or being in the room, should I treat that as potential attack? If yes, I will ask followup yes-or-no questions about appropriate responses." This feels like a bizarre question to be asking about a hotel, but Belmarniss said the city wasn't perfectly law-abiding and it's much better to ask than to risk misunderstandings later.

Belmarniss nods!

"In such a case, should I preemptively try to nonlethally disable whoever is there without waiting for them to explain themselves? They may incur some broken bones. ...competent people might be able to enter without waking me and if they do they can kill me before I can act if that is what they want, so we are talking about either incompetents or people who are not prepared to use lethal force. If given the chance, should I preemptively try to at least disable them? If yes, my next questions will be about lethal force."