So far these are the people I have been able to deduce on tone and common mistakes in speech. Arthur is the exception of this of course, I do not believe Yayap to be so easily tracked but it is a possibility I can't ignore.
Janice - McPwnage(Or someone faking McPwnage)
Deirdre - Philie?
Riley - MrSmarter / McPwnage
Lois - Probably Plato or someone trying to use Plato as a shield
Arthur - Yayap or Fred / Falsetruth trying to be Yayap
Jaret - Oops or Suicidaln00b, no doubt.
Role List thusfar:
President Shinra (Godfather)
Rufus (Consigliere)
Hidden Mafia role
Hidden Mafia role
Reno (Framer)
Elena (Consort)
Hidden Mafia role
Hidden Mafia role
Prof. Hojo (Cult Leader) - Katherine
Sephiroth (One Winged Angel)
Yuffie (Ninja)
Hidden Benign Neutral
Hidden Benign Neutral
Cop (Sheriff)
Investigator
Aeris (Doctor)
Journalist
Barrier Materia Trader (Armorsmith)
Hidden Town Power
Hidden Town Power
Hidden Town Power
Hidden Town Power
Hidden Town Power
Hidden Town Power
Hidden Town Power
Cetra Ancient (Mason) - Highly likely to be Riley
Citizen - Yren
Citizen
Citizen
Citizen
Citizen
Citizen
Citizen
Citizen
Citizen
Citizen
I won't presume to be able to deduce anything beyond that, anyone is welcome to contribute to these lists, but please be sure to provide reasons.