She isn't worried over that , her thing is that she knows the original person treated the boy badly and he killed her for it. She is trying to change that part of the story thinking it was her fault that he turned out that way, not knowing he was already that way from the get go...
It's less about her being dense and more about her being from the modern era. She's from our era and the thought of putting kids through that kind of training and trauma even if it was necessary for their survival for what ever title they had, would have people putting up the pitchforks to get those kids out. We do everything we possible can to make sure kids are safe and dont suffer, that's what the FL lead knows.
I’m sorry but I don’t like the FL. She’s so annoying, like how dense do u have to be to not understand the consequences for Ain in the future if he didn’t do the training as everyone is gonna be trying to kill him. Sis u ain’t saving him, your gonna be the cause of his death if u keep this shit up (ಠ_ಠ)