> That has the about the same potential for bugs I guess.

* DoWealth doesn't take an object
* GetOwner asks stuff on an object you already have. How does that interfere?
* GetPower? Whether objects in different layers should be effected by power / ownership radius is debatable. I'd say they shouldn't.

Back in Clonk Rage I did a search-all on FindObject, and almost all of them would have needed the layer check. The only exceptions would be stuff like global counters, e.g. counting all objects to get the current score or get all objects for a section change.

Layers are mostly to be used by missions / adventure scenarios where the scenario designer puts stuff away from interaction. E.g. they can turn a workshop into a decoration object. They can protected an important NPC  from being hit by spells and pushed off the cliff. Another use would be for hidden stuff in e.g. enterable buildings. In either case, it's specialized scenario settings where the author of the scenario will notice if any searches that need to catch these objects skip them (unlike e.g. free settlement, where the players might build things the author did not think of).

> PS: How does CreateObject behave? Does it create the objects in the layer of the caller?

Yes, it should do that. I built it like that in Clonk Rage. I don't know if that is still the case.

> PPS: What about attached objects - do they adjust their layer to their parent?

No. For example, dialogs are attached to NPCs. You often want the NPC to be protected by a layer, but the dialog object should be accessible for talking.