I think it made more sense to have the same DC, yes, but I don't particularly support changing it at this point. The changed dc does not meaningfully deny player agency. Now, with that being said, I do think it's also worth considering the dc in general. Usagi is a diplo specked character, and yet still has a readily failed roll to explain basic facts. This would imply that, for instance, Ami is essentially categorically incapable of explaining this since her diplomacy is 7 lower, which I feel probably isn't what you want.