I dunno! I say Aeris and think Aeris, but when I write or type the name I spell it Aerith.
Yes, it was definitely a mistranslation. Kingdom Hearts is correct calling her Aerith.
No, it was NOT a mistranslation, and Kingdom Hearts only called her Aerith as fanservice.
I'm really indifferent on the matter.
*Poll Option Under Construction*
I dunno! I say Aeris and think Aeris, but when I write or type the name I spell it Aerith.