Ran into this while fixing dialogue (TR_m4_sashnakh_gra-lash was casting a nonexistent spell that I replaced) but currently the quest Find a Lost Comrade in Rith-Ilviryon (TR_m4_wil_RithIlviryonLost) cannot be started due to the fact that aforementioned NPC isn't placed and the tomb you're supposed to go into isn't linked.

I presume this is intentional as the tomb is humongous. But still. It's in the files, and we ought to do something with it.