I've had two seeker events, which I survived with no real damage to the base. Compare that to the two trolls who just smashed trough my stake wall. Even with a trench, they can damage your buildings by throwing rocks.

Gjall event only happens in Mistlands. So just don't build bases in there, until we get some more defense options. And I agree, buildings should have a lot more resistance to gjall/seeker attacks.