revisions unmapped comments

If a comment is placed on an object or text and the object or text needs to be deleted, then the comment gets unmapped. The commentor when checking back on the comment has no way to see on what page the comment was originally, and it is quite impossible to check if the tasks in the comments were executed properly. therefore unmapped comments are big issue. Even more without a history. For a starting point it would be helpful just to map the comment where ist was last before getting unmapped.