I actually really am proud of the setup, and I kinda wish I'd held it until some players got a bit more used to Mafia and specifically my games, because I think some were overloaded with the amount of info to parse. A lack of familiarity with the theme probably didn't help either, but I don't regret that.
Basically, the core idea of the series is that Science and Magic essentially exist independently of each other, so I wanted to reflect that with the seperate towns. The Science side needed SCHOOL to live through the game, and the Magic side needed Necessarius. Touma, of course, needs to save everyone, as he's the protagonist, so for him to win, both Science and Magic towns need to win as well.
Mafia needed to be able to adapt throughout the game. Hence why they had no role that was strictly tied to them. If they were getting thinned out, Othinus was a behemoth who could only be stopped by an Index redirect or a Kanzaki kill.
For the Indies, Vento hates Science, so her thing was, if she were targeted by Science-side characters, she'd be able to retaliate. Her main magic is to punish those who show hostility towards her, hence how her whole mechanic works. It's a shame Divine Punishment never came into effect, but it was quite conditional. Fiamma, on the other hand, his power is to scale up one better than whatever he's facing. For him to beat Othinus, he needs to fail a kill on Index, which for flavour, would give him the forbidden knowledge she holds which gives him the capability of killing Othinus. Otherwise, he needs to get rid of Vento, and Touma. Mostly to balance the books, as Vento was already very Anti-Town. Fiamma killing Touma once satisfied that part of his wincon, so Touma coming back was the least harmful role towards the town that could still hurt them.