Well... The scope of the aggression is not bugged. Becoming hostile with any Tiefling will set all other Tieflings against you too.
As far as Guex confronting you, this can occur with any adult Tiefling if Mol doesn't like you. As she will go tell adult Tieflings about you when she runs off.
From what I can tell from your context, although you have completed some of the tasks that can cause her to like you (Helping Mirkon and Meli), your dialogue with her resulted in upsetting her. Hence she went to go tell the adults and you were eventually confronted. It just happened to be Guex who confronted you.
