Seems like that is something that could possibly be fixed automatically by one of the staff. They should be able to do a query to find all taxa with a subspecies or variety that does not have a corresponding autonym. I don’t know if they could mass-create the missing taxa though.
Looking around, I found a post on the opposite problem here:
https://forum.inaturalist.org/t/single-nominate-subspecies/11004
As @loarie was involved in that, maybe he knows. Unlike that problem, this seems to be a case where people wouldn’t need to individually assess each instance. Creating missing autonyms causes no taxonomic issues and they can be lumped if needed if someone ever lumps the other subtaxa within a species.