Although I agree with faust that the set-up isn't necessarily unbalanced (just harder work-wise for scum), it might be too swingy. I think a couple tweaks could help with that.
I think the set-up would be more fun, if there were only 3 scum, but the actions were tweaked to give scum more options and to make coordination more problematic. In particular, it seems to me like scum's best options in the current set-up involve taking the pro-town powers in order to prevent town getting full value out of them...but then if scum fake-claims, they have to figure out some ineffective action they could have taken. And even then, claiming ineffective actions can leave scum exposed if town's actions were largely effective.
I think the lower deck blocks night-kill is a bit overkill, and could be removed.
And then, say, lower blue Sabotage was "Cause a player's card action or movement to fail." This would open up scum's fake-claim possibilities because if they claim a failed action (when they simply didn't attempt it), town has to allow for the possibility of sabotage. It also really hinders full coordination because that tells scum exactly where to use a sabotage to hurt (and again scum that fails to take their coordinated action was maybe sabotaged out of it).
Some other thoughts:
-Lower Red/Blue could have A and C swapped, limiting town's monitor abilities.
-Another sabotage action (maybe lower-central C?) to "steal" cards from another player (maybe reduce that player's free card draw to 1 for that turn? So it can't stack to lock someone out, but it really hinders town's options, and makes them want to use the card-draw as counterplay?).
Possibly offering sabotage options in upper A/B actions, still costing energy? Like if, the cop-switch was a sabotage on upper Blue A...then scum can go for it, and then fake-claim that they've used weak visitor. Status printout denies their fake-claim then, but that's no worse than the current situation, and if the only status printout is in scum's hands it really opens them up.
You could also do sabotage in the form of, say, "Strongman" so scum can force a nk through any possible protection with the right card-play.
I think daychat is a good idea. It's tough enough to detect a lie, which means working out a good enough fake-claim is even tougher. At least with daychat, if you have just one player that can work out the lies you can get a safe-claim for everyone. Whereas, without daychat, you need each scum-player to be able to come up with their own safe-claim.
Although ultimately playing scum is going to take more work in a set-up like this (simply because of the amount of info potentially available to town), I think that work can have significant pay-off if scum has the tools at their disposal to frame town.
Final thought: near-unlimited nightkill protection for town is, I think, ultimately OP. While letting scum "fail" any single night-action could help with that, some sort of ability to overcome it is probably ideal. As it is currently, you can essentially force scum to help block the nk, and they can't do anything about it. If scum has a power to pierce it, then you don't know whether someone failed to help stop the nk or if scum got in a pierce action somewhere.