I completely missed this post somehow, so sorry for the late reply!
I like your concept of splitting the power into multiple roles, and it looks well thoughtout overall. Things that I would consider changing are:
Maxwell's Demon: This role can potentially confirm 4 players every night per Demon in play, if there is one mafia known or soon to be known. Players could even exploit that by keeping one mafioso alive as a target for this ability. As an ER ability that can easily be given multiple players (as Nymph's ability is ER, too), this is prone to snowball really hard to victory and is almost impossible to check for the mafia team.
Now, this is only one of two roles to directly check for mafia players, and Firefly is rather weak (to make sure: will it be known whose role is given out of the 4?), so taking that part out seems like a poor choice. You can add some restrictions like making it EoR and/or making it 1U or 2U. We can discuss other options if you are up to that.
Nymph Queen: Likely the core of your setup, and sounds fun to play with. I would simply cut a few roles to never be given out by it, like Council Member and Guardian Angel. Just be sure that some strong additional roles early on might make for a big swing, which you intend to avoid.
Mass Roleclaims: This goes up and down whether PMs will be allowed. If they are, a mass roleclaim will happen sooner than later and lead to a rather boring game. Having hosted a mafia with and without PMs, I generally recommend banning them. As you have no direct way to punish mass roleclaims as a mafia player this game, it is especially important to keep them in check.
Number of mafia players: Making a quarter of the players mafia is the common rule of thumb for mafias on this forum. I checked through a lot of older setups to get a good feeling for my setup. If you want more players to be mafia than usually, you should bump that up a bit. However, depending on how this setup evolves before it goes live, check closely how many ways town has to actually find mafia, and how powerful mafia is with the ability to grant additional roles with their Nymph (but also the risk of getting caught).
Are you up to host soon when the rules are finished?
Note: Linkcat is pretty busy right now and I'm just taking the initiative to keep it going. You will still have to talk to him about the set and when it goes live.