Could be both that, while the many fuckups on Niji, their dynamic with the different waves being parallels/opposites to the prior/following gen, could be the case that, since with Myth and Council, for the most part, they are unrelated to each other, as they are more so different core concepts, while with Advent, they had already the narrative in mind of being part of "something grander" as to why now they decided to do a tie in with this upcoming EN4.
I like it, and in some aspects, you can sort of fill in the gaps, as to which of the respective Justice members would be going against in terms of the Advent members. I also really like the small but on point "Catch us if you can...!" that the Advent members drop at the end of the PV, nice touch.