So, I'm in Kuldahar, and am trying to fulfill the quest with the villager and the 2 yetis. He still seems to think that one's alive, even though I've long since killed both of them. Is there a variable I can set to deal with this frightened twit?

What is the version you're playing?

Also you need to talk to Mirek as soon as you kill the 2 Yetis. If you wait until later, it doesn't seem to work.