Pleroma update activities will be a reply to the activity that produced the version they modify. This does not change meta data on the object itself:
As for federated move, I think this is an issue unlike any other CRDTs may have encountered because they have distributed documents, but the document hierarchies are local to each participant. At some point, ActivityPub will be mixing shared document hierarchies with personal ones. When that happens, the author of a move will have to decide whether to list or simply identify source and target collections and whether to munge the move activity, itself, to avoid leaking metadata about collections the actor isn’t sharing