Well, the admins can edit/delete the game if it isn't a part of the series/is a meme board.
I can't think of a reason why a moderator would abuse their power in this way. Creating fake boards doesn't really inconvenience anyone that much (except maybe the people who have to delete them). But if a mod were continually creating bad boards, I'm sure they would quickly get their privileges removed... and nobody wants that do they :^)
Yeah, just like with any moderation issue, if a mod is abusing their power in any way, report it to a full mod or admin and they will deal with it. Part of being a moderator is a degree of trustworthiness, so most mods won’t intentionally violate rules for games or series.
Also, not sure what you mean about rules regarding submitting ILs. ILs are a game by game basis and have nothing to do with series moderators.
Games added to a series are added under that series so it's very obvious when people are doing this. It's been this way for years with minimal issues. The intent is to allow series moderators to add new games. If people can't handle that responsibility with basic sensibility, then we can remove them.
Full combo runs. If you mess up, you do the song over again.
That's the only way I've heard guitar games being conceived of as speed games.