I really disliek how our heroine decided that the reincarnator is suffering from mental trauma and then getting her name dragged through mud in school is perfectly fine as she is used to her insane bitch of a grandma being like that.
Is not normal and no, you shouldn't let someone in that state act like they are right and do whatever they want, MC is not a doctor and a young kid acting like that should get checked by professionals.
Yes, we know the reason why the reincanrator acts like that, but in a world with a minimum of common sense the kid wouldn't be left rampaging.
This is a gimmick to push MC accepting whatever happens, when after years of unjust suffering under the mad grandma she should refuse a unknown mofo to do the same.