I am kind of on the opposite side of the fence in terms of Hildibrand. I like to imagine that those quests absolutely occurred as we see them. So far as I know, the power level of the Mandervilles, while stronger than your average person, are not that far out of there compared to all sorts of people we've seen as bosses or in FATEs. Besides, sometimes life just gets weird. I'm sure everyone has had experiences where they have to ask themselves after the fact "Did that just happen?"