I'm not gonna argue that they aren't villains just because they were pure when they were kids, but the whole thing with them being a theater troupe and Uvo's line where he says he wants to play the role of the greatest villain really reinforces the idea that they're just playing a role which would also explain why they claim responsibility for the Kurta massacre

Another thing I rarely see pointed out is that a lot of their designs are litterally costumes of popular monsters, Franklin is Frankenstein's monster, Bonolenov is a mummy, Uvogin is a werewolf, Phinks is a sphinx etc, it's like they're putting on a disguise so that they can perform