>>103254521If we're just going strictly off the lore and putting aside how these girls actually act, I think it's fine for Justice to be more lighthearted whereas all the gens before have been more morally ambiguous.
The vibe they seem to be going for is more heroic, though with the layer of silliness in that they suck at being heroes - ERB is too easily manipulated and the others are just too lazy and/or easily distracted. I think this works as an intentional opposition to Advent, who are increasingly being framed as villains.
The latest Justice song they put out (which I didn't actually like very much honestly) has a somewhat darker tone though, possibly implying they're going down a corruption arc where Justice becomes more brutal and unforgiving in their pursuit of Advent, and that's where the edginess would come in.