I accidentally ran into these two tags while trying to find for correction.
The purpose of Fixme is to be a request for someone to clean the image of scan artifacts and all that, which would make them a third-party edit.
The purpose of Fixed is to mark an artwork whose scan errors have been fixed by a third-party.
I think the latter tag was supposed to exist as "answer" to the former tag, since i believe the number would be much higher otherwise.
I think fixme should be nuked, since it asks people to edit artworks and upload said edits, while fixed could either be kept as-is and gardened, aliased to third-party edit, or just nuked.