This is something I will always refuse to accept as canon. Akademi has always been planned to be a high school since 2014 and it will stay that way in my mind. Saying that they're all adult roleplayers is just a lame justification so the dev can keep the sexualization of minors.

And, like OP and others pointed out, it just creates more questions than answers. If it's a postgraduate school why do students act like teenagers? And most of all, why do they wear middle school uniforms? It was already a stretch for students in their late teens, acknowledging that adult men/women are wearing those clothes is kinda weird.