The players say that the stability of all entities is always 100% which makes it harder for them to raid.

this is intended, otherwise some buildings can fully or partially collapse. you can disable this in paste options by changing setting stability to true, but i suggest you leave it as is

the only solution for this is to have the CopyPaste plugin restore the stability of the building when it's pasted. way easier said than done, though

Thank you for your answer.