These are the official classes. Out of these here, it is confirmed that we have Scouts, Demomans, Heavies, Engineers, Medics and Spies. Only Snipers, Pyro's and Soldiers are missing. Probably, snipers are the vigs that we know that exist.
So far, we know for sure that Deku included 7 classes. 7x2=14. 14+4(arguably the amount of mafia)=18. This leaves 2.
I am quite confident that this means we have another pair of townies. It's not unthinkable that Deku added third party. But, I have a few reasons why I believe he did not include them:
1) There is no Serial Killer. We would probably have noticed that by now. This would imply that there are 2 non-SK third party roles in the game
2) The inclusion of 2 non-SK roles seems unlikely. e.g. 2 survivors. 1 SK and 1 survivor for example wouldn't be impossible, but 2 is a lot.
3) In Deku's original set-up, he asked for 23 players. Contrary to the current 20, this is an unequal amount. If you multiple the 9 classes by 2, and add the 4 mafiosi, this leaves 1 players left: probably the third party role.
The most likely explanation is that when Deku removed roles, he first removed the third player role and after that townies in pairs of 2 (he also requested people to join in pairs, in hindsight to full op both the blue and red versions of town roles. So this supports my theory).
Having established that there is no third party, we can say with a lot of confidence that there is probably 1 town class left that we have not yet discovered.
The big question here is, does that town class have a power or is it a powerless class like engineer and demoman?
So far, we know that there are 4 VT's in the game. 2 of them died (hence we know, because they both still have their living counterparts). 2 other people (soft)claimed VT: Frozen Chosen and Ver-Go-a-Go-Go. This is important because if we know for sure that there are only 4 VT's and no one else counter-claims, we can be sure that FC and Vergo are town. This greatly solidifies our already strong position, might prevent a mislynch (e.g. Vergo) and gives us more people whose analyses we can trust.
For this reason, I want to ask everyone. If you are a townie from the 8th class, a class that we have not yet encountered, please soft-claim and answer my question: Do you have a power or not?
Do not specifically tell me what power and whether it works on odd/even days, just whether or not you have a power is enough. If this 8th class is non-VT, we know there are 4 VT's and 4 people that claim to be one. We can then ask the next question around, for everyone who truly is a VT to counter-claim (because then we know that either Vergo or FC is scum). If this doesn't happen, we know Vergo, FC and probably the one soft-claiming the 8th class* are town. If the 8th class player says he has no power, we know that there are not 4 but 6 VT's. In that case, we have 5 VT's and one spot left. So, no, we cannot yet firmly confirm Vergo and FC, but with having 5 out of 6 claims we can easily confirm that tomorrow, and we have the player who soft-claimed the 8th class as a confirmed townie.
So by following this strategy, we will at least confirm 1 townie today and possibly 3.
We are close to finishing the puzzle of this game. Just a bit more and it's game over for the mafia.
*We can also be quite confident that the one soft-claiming the 8th class is town. If he/she claims that they have or do not have power whereas this is a lie (50% chance) the real players from this class can counter-claim and we will have found scum. Even if they guess correctly, as soon as accidentily one of the real players from this class die, there will be only 1 spot left and 1 who claims it. If there is secretly a second who knows he/she has that role, he knows that the one making this original claim is lying and can then counter-claim. In other words, it is suicide for mafia to fake this soft-claim and so whomever makes the claim will have my trust.