I made a list of tags that contain unicode characters, since they're generally not supposed to be used. These tags have 1 or more posts in them. Some of them use invisible characters or letters that look non-unicode.
arai_harumakiero_doll_☆└(^o^)┐≡n℃zelos/0surikohime_(kagami_no_machi_no_kaguya)n●va_sacchinikm♂凸凹miyabi★mt.bikusa∞ane_suku_~_wagamama_!_ane_to_sukumizu_yuuwaku_tokkunyama_(two:five&seven)aki⑥halno_ichigonaked_gun_33⅓36号9193℃come♥uma(v)・∀・(v)saiga_(祭画)4℃oyunomi_iica(asoo2)2aqneko_neko_☆_super_fever_night_(vocaloid)n→rgogo_no_abatīkiyose_kenkyū-inblaze(改名考案中)para☆isohakaokuri_no_uta_(vocaloid)p@sta(。•ㅅ•。)уjounetsu_no_lovers_♂jounetsu_no_lovers_♀focke‐wulf
These tags are not unicode but are under 0x008F in the first character block or really shouldn't be there in the first place. None of them have more than 4 posts:
surströmmingfévrier–eden*_they_were_only_two_on_the_planetre°kaniehtí:iotim_löchnermai_françois_joymajimbù°w°n*madchennn*mikaël_aguirrejérémie_périnnazgûleiki`sweet³_roomshi*ki_(sm041yh)josé_luis_rosadomichaël_crouzatfaldhatéeshenyíng_ehuosaara_mäkinennürburgringmanuel_xavier_rodríguez_erdoízalet’s_try_bass_fishingjamie_(let’s_try_bass_fishing)fortissimo_exs//akkord:nächsten_phasedéméchrelle_(felarya)mistéxpiacetea_rémi
They use one or more of following characters: *`’•–°³äçéëíöùûü
Kudos to ghostrigger for fixing the majority of them!
Updated