Powerscaling isn't supporting evidence, feats are. Of course Goku and company would grow stronger as the series progresses. For the multiplier to be supported, there needs to be a direct feat in the same range at the same time. In short, there needs to be a direct feat in Buu saga that supports the multiplier for Buu saga. Unfortunately there isn't. You're also neglecting increases from training, zenkai and other transformations that led to SPC's solar system statement. You can't say all of that was because of multiplier boost.
I think we are talking about manga only here. Kid Buu isn't 4-A in the manga for busting a galaxy over time.
DBS speeds come from their own boosts. They are not supporting evidence for anything in Z.
Which is okay. You don't have to agree with every wiki policy there is, and neither do I. But it is a wiki policy. A massive multiplier definitely needs supporting evidence because, yes, the numbers are too large and require evidence in the same proportion.
I would have also proposed to wait before concluding this thread, seeing as Zamasu and/or I were planning to create a thread soon which would somewhat affect the results of this thread, but I guess the changes were already made and I was too late?