I’d make a catch-all “colored changeling” (might not be the best wording) tag as an implication of those tags, if not as a replacement for them. The main reason I could think for having distinct color tags is if there’s a clearly-accepted fanon distinction between these different colors of (primarily-unreformed) changelings, and I don’t think there is. Otherwise, why not have color tags for other species? I’d rather not have to tag colors of everything like you see on e621 or Furbooru though.
I see zero reason for “christmas changeling” though and think it should be done away with.
I’m not a changeling connoisseur, so I may be off the mark here. Might be worthwhile to personally reach out to the one who adds these tags frequently (as big personal tag projects tend to be frowned upon anyway), as well as others who may know better.