So out of all of mine the most obvious of who might know her is Evan. He would have been a year below her in Ravenclaw and I think they could get on? I would say 'they could've been friends' but I'm concious of you saying that she didn't have many friends in school and I know your history for her said that she didn't necessarily get along with her housemates. I don't think Evan would have been mean to her, because Evan doesn't do that, but he could have easily just... not talked to her? IDK. Let me know what you think.
As for the rest of mine... Higgs, Oliver, Aisling and Jun won't know who she is. ALAS. Zac, however, could (and probably would) have very easily bullied her in school. Zac is not in any way tolerant of people who stand out and Luna definitely would've stood out. He is also a dick. So yeah :/