He's not trans, she's just given one of the most gender confusing debates in the history of FNaF (next to mangle)
When I was younger, I assumed that there had to be a few key factors to determine the gender of an animatronic: eyelashes, rosy cheeks, lipstick, slim body, feminine voice
looking back i can see how poor those factors were once i realized FNaF 1 chica was a girl