I'm also of the mindset that there is no real need to split the leaderboards at this time since there aren't many runs of the PC version. Sure, BBS might be slower on PC but it's not significant enough to warrant a split. If you were to split it right now, it would look empty, especially considering how many different categories BBS has. As others have said, if interest spikes with the release of the steam version, then we can return to this in the future.
As for mods, I agree that we need to look into seeing whether or not they can effect the RNG of the game in anyway as RNG plays a significant part in the run, no matter the category. If mods don't effect the RNG, then I would be okay with a soft reset mod & that is all. Allowing cosmetic mods to me feels like a slippery slope that could be hard/tiring to regulate.