So based on your "Spoilers" here are my notes:
Citizen - They should have 1 Seance when they are dead to let an alive town member know who their attacker was. Also, what happens when multiple townies are attacked? Does the Citizen stand up for all of them or just one? If just one, how will they choose which one? Finally, I think the name should be changed to Police Officer or something, Citizen doesn't fit this role.
Daggerman - I like it
Silencer - What do you mean "there can only be 3 people silenced at a time?" Also, this role is too confusing for me.
Hypnotist - There are too many hypnotise immune roles. Also, I think you could just add the speaking for the person you hypnotised part to Blackmailer's abilities. It's so close to BM'er role, because they can silence people at day, too. If you do do this, then take out the no voting next day part.
Avenger - I don't like the "Abilities" statement. I think the Avenger should be able to use his ability at least 4 times, if not every night. Finally, Lookout should be able to see him, otherwise he is too well hidden.
Observer - Way too close in ability to Lookout or Investigator, but nice idea.
Poison Expert - So when someone is infected do they die? And what does "You will not be notified of your infection" mean?
Traitor - I'm sorry but... This role seems pretty unimportant, useless really, and doesn't make any sense.
Diplomat - I don't get this role.
Necromancer - What is an Imposter? An what happens when the person dies? I'm sorry, but this role is too confusing which makes it, in my opinion, useless. It also is too unfair to the town.
Officer - This role is too close to Jailor & too complicated.
*Remember, this is all constructive criticism, just helpful ideas.