Kashtan probably means the small excavation with the ladder inside. Cavern is probably not the right term for it. Where Alice and Yulya are supposed to go. Cat has no issues and will go to the position on Kashtans map. Something like this. Ashley ended up as catboy somehow.

Cavern?

Yulya tries her best to ignore the bickering but the lantern is something she cannot ignore
Ashley thats enough! If your summons  are only here to play pranks on us despawn them. We do not have the luxury to fight among ourselves down here.
Cat set up a lantern at your position and fall back! I do not like these tunnels at all. As there is no immediate danger north let us continue eastwards along the tracks!



Yulya casts LIGHT on a rock and tosses it into the tunnel
Alice please go check out the cacerb with the ladder you mentioned! If that cavern is safe we can move there.

If the alternative scout summon named Alice finds no danger Yulya moves into the cavern with the ladder.

"You better not bother Mrs. B, and if I'm interpreting everything correctly,  I was killed, my soul was taken to the negative plane and reborn as a mechatherial panther, then cursed to live as a human and summoned to the material plane for an unknown timespan."

I believe Cat said for Yulya to stand behind the barrels while she went North to peek East.