https://www.mediawiki.org/wiki/Manual:RevisionDelete
When a username / IP is deleted from a revision that info should also be removed from the contributors db table.
And of course if a revisions user is restored it should be re added to the db!
The extension will have to make use of the ArticleRevisionVisibilitySet hook.
https://www.mediawiki.org/wiki/Manual:Hooks/ArticleRevisionVisibilitySet