Additionally on top of those reasons, the Calculations currently being used for speed scaling have a lot of issues from being outdated, has contextual issues in the narrative of the story, wrong sizes being used, are outliers, has circumstances surrounding them so scaling from them shouldn't be simple, or just in general contextually makes no sense (Plot induced stupidity or outlier)
And the The calculation that is currently being used for Seiya (Aside from its visual issues) is being used to scale to characters with a fairly weak justification for several characters. For examples "Should be comparable to chapter 1 seiya" doesn't really sound like a good justification.
Also just in general, the profiles are in a terrible state, and several CRTs have been done and no one updated them.