@ElizLestrad
I dunno, it depends. Interactions between friends are largely dependent on the personality of each person. Sometimes, close friends constantly insult each other while other close friends will keep a respectful distance. If the person in question was Sora and everybody was ganging up on her, that would be toxic. On the other hand, Haena seems to not only be fine with it, but also thrives on such attention.
In this case, I think this is a fairly healthy relationship. Haena's lack of brains is not only well known, but Haena also doesn't consider that a inappropriate topic to rib her about.