I had an incident where a stack of zombies attacked a settlement and had superior strength, but lost the saving throw and were also wiped out. There were no survivors. With no zombies left, the settlement survived. However, because the mortal army lost, their restless souls remained.
I didn’t want the bodies to rise and wipe out the settlement, so I spawned a hero card onto the settlement. However, before the bodies would be burnt, I had to move the unit away from the settlement, then back into it. Apparently bodies only get burnt when entering a location.
I think it makes sense that the settlement survived, but it seems that the civilians would have been able to burn the bodies. Even if they don’t, I think that spawning a unit on top of bodies should result in the bodies getting burnt without having to move that unit off and back onto the location.