This is probably not a popular opinion, but I'd love it if Cyrillic letters were allowed in names. I have quite a few Russian-named pets that would be just a smidge cooler if they didn't have to be transliterated.

But I think that's probably a whole different can of worms to what you're proposing here, because it plays into the whole English-only thing (not everyone can read Cyrillic), among other issues.

My pet Aífe would love the correct spelling of her name so an expanded letter pool would really benefit me and I"m sure many others!

Cyrillic might be pushing the envelope a little, but I certainly wouldn't mine its inclusion (or even including Katakana or Hiragana syllabary) but the fact that they're completely non-English characters versus just accented English characters may make them automatically declined.