The LM temple is coughing up the 2500 of the 5000L, yes. 5000L is a hella lot of dough for these documents. This is not unusual behavior for Black Fang, they have no official ties with any city cult, but rather do as they please. Their members are unknown, so on an individual basis their members have no problems dealing with cults that hate BF. The BFs seem to know that the docs are worth a lot to someone other than the LM cult. The LM cult promises Idylla that she will have full access to the papers in return for arranging their retrieval (of course, so will Tison).
Idylla is pitching in all of her cash, 500L. Vera will add 200L. Anyone else is welcome. So you need about 1800L.
Cholobo: I forgot if I said anything about him before, but here's what he finds on his free time when he searches the spirit world for Morta: he is not there. Morta did not complete the 7-day journey to the underworld. Cholobo says that he appears to have returned; you would surmise that the Black Fangs, whose priests are shamans, have recalled him as a ghost. Shee-it. Bet he's pissed.