BUR #5921 has been approved by @evazion.
create alias asymmetrical_pupils -> mismatched_pupils
rename asymmetrical_eyes -> asymmetrical_irises
mismatched_pupils: wiki just says different pupils, currently used for both different-shaped and -coloured pupils.
asymmetrical_pupils: no wiki, only 16 posts, mostly different-shaped pupils with one example of different-coloured pupils
I think it's fine to lump all types of different-colour, -size, and -shape pupils together, there's not a lot of this and they're frequently together in one pic. Even if we want to separate these concepts these tag names are far too ambiguous, so something like different-coloured_pupils would be needed.
asymmetrical_eyes: wiki says "Eyes that have noticeable difference in size or shape", in practice it's a mess of mistags for uneven_eyes, mistags for mismatched_pupils, and a handful of instances like post #3827690 or post #3514327 of eyes where the whole iris is larger in one eye than in the other. If there's no objections I'll garden all but the latter out and write a better wiki. I didn't see any examples of different-shaped irises, but they'd be fine under this tag if they're ever found.
The only problem is that asymmetrical_eyes remains a hopelessly ambiguous name, and the mistags will definitely continue. So I'd also like to suggest a rename to asymmetrical_irises to prevent future confusion. After all, the difference in iris size would be what makes this tag different from the others. When the whole eye itself is bigger, that's usually either uneven_eyes or just perspective.
Nearby, there's mismatched_sclera, uneven_eyes and heterochromia, but they're decently well defined and consistently used.