Telrav has two packages, TelravTravelStage20Alive and TelravTravelStage20Dead. Alive has as a condition that all three guards are alive, and dead has a condition that all three are dead. If some of the guards are dead and some are alive, Telrav has no package that can account for that situation, so the quest locks up.
I got a bit fancy with this and made a new "Some dead, some alive" package that will account for this case and will add the still-living "guards" to the correct aliases.
Additionally, for some reason it's only checking three bandit guards in the conditions even though there are five. I've fixed the packages to account for this.

Attached Files:
USSEP_PF__0B005900.psc
nilheimfixc.esp