I’m sorry, but you’re wrong. Depression has been know for centuries (in our world, thus theirs too); many people called it melancholy, sadness, imbalance of the spirit/mind, etc. These f*cking bitches who call themselves her “family” had access to this knowledge, BUT CHOSE TO IGNORE IT! They chalked it up to rebelliousness (as if committing suicide is such a petty thing) when HELLO?!?!? SHE WAS TRYING TO KILL HERSELF!?!!!!
you literally explained it. It wasnt "depression", it was melancholy, sadness, etc. And, in our mc's case, it wouldnt have seemed like those, as she wasnt acting sad or slow, she was acting rebellious, rude, and causing trouble-she wouldve just been considered a bad egg, or manic. The suicide was likely chalked up to said mania, or perhaps an attempt at attention seeking-though it did also cause them to take notice of our mc more. Also, in the original story within the story, she actually died, so we dont really know how they responded to her perma-dying.

It’s hard to remember that those same people that are protecting her, drove the OG to suicide and blamed her for having chronic depression