I don't see any problem with Ronan being 8-A. James Gunn
specifically stated that “We’ve had the Other, who’s obviously very powerful even in comparison to Loki, and then we see Ronan wipe his ass with him.", a choice specifically made to establish how much of a threat Ronan is, and it also seems to essentially confirm that The Other is superior to Loki. Ronan being 8-A shouldn't mess up scaling, considering none of the Guardians of the Galaxy scale to him, and he's presented as being far more powerful than other Kree.