@Veshv absolutely, I've also mentioned that my theories have been wrong 95% of the time, it's just fun to try and predict what's what.
The author really likes to mess with time in his narratives, memento-style, so I wouldn't be surprised if Nowa had already noticed / mentioned something unknown to us the readers. I also suspect that the Nowas may have been the one consistent element in Kakerou, and who's to say that they don't actually benefit from the Kirumas being the leaders, thus keeping things hush hush would be in their interest.
But then again, Souichi has been with Kakerou since a child so any hypothetical overthrowing would have happened when Baku was also a child, i.e. not necessarily known by the refs (assuming they are the same set as from previous generation), and easily handled by changing his last name.
The one thing I'm still trying to grasp is Kaji's role in all this, as Baku seemed to have purposefully targeted him (ate his kariume in the middle of Ch. 1). There was a dream / flashback sequence in Protoporos (I think during Baku's nightmare when encountering Bai Long?) - something about "my child" from an unknown voice - which I thought at first was related to Marco, but I think (hope, lol) Kaji may have deeper history than we know of.