The devs have said that no one in the school has a mental handicap which disqualifies ADHD and COLD, as fitting as they are. My guess is that her malfunction is WAHAHAHAHA~!
Misha obviously has less severe hearing problems (She has problems controlling the volume of her voice and has expressed inability to hear Hisao when he's whispering...it also explains why she knows sign)
Plus some kind of motor control disorder. She always goes on about her clumsiness to the point where she cant even break chopsticks evenly, she recalled one incident where she was trying to build something and ended up nailing boards on top of eachother and getting laughed at. Also, stairs make her dizzy. This is too much to be simple clumsiness and the only hints that have been dropped for her malfunction.
