"Notice: Gaming experience may change during online play"

Lawyer words to say that idiots online can screw up your happy place. At some point, if they have the keys to the kingdom, it can happen. I can't see how if you have 3 people, A,B, and C where you are A, how can C be mad at A if B did something? This implies that C is unreasonable and not much of a friend? I can't imagine being mad at someone because someone else is a jerk.

I agree there should be logs to see who did what -- every item created in the world or stored in a chest should be marked with the ID of the person who created it or stored it. And every time an item is destroyed or taken by someone with a different ID, it should be logged. Terrain editing that that results in destruction of other players' things logged as well. Sounds like maybe also boss kills & trophy hanging logged. Not sure what else.

And we may get that at release, but its not there now :(
all you can do is make frequent backups and try to figure it out.