Talking through some stuff with Francisca and I found a "plot hole" in the reason one of my groups is there.
There are there because some got Quested in return for a Heal spell (clay automatons are bad news), and the cleric of Ymir (the church they visited) agreed to do basically the same but without the spell. Something about free will...but they didn't need Heal'ing.
In any case, the quest is to go bring the head of a falso god and if possible its crown.
That is my hook for Forgotten Fane.
As it turns out the church didn't tell them about the rest of the place :-)
I don't think it's a hole so much as the temple focusing on the coiled goddess from what little info they got back from the people that journeyed there and back.
They might also have problems with the other gods (well, those not in the "main" hyperborea pantheon) but that's a different problem.