Workshop

Well, the GM needs to create 3 different blockers, 3 different checkers, 3 different doctors, etc., and each of them should be approximately equal in abilities.

Balance is difficult not even because of that. The town will simply be "what's going on, who are all these people" during the day. Here, either clues need to be given that are very clearly discernible (but not in direct text), or the town needs to be given a stronger advantage (but then it's easy to overdo it and they won't have a chance), or some role that can identify the characteristics or the random roles present in the game, and that this role must appear...

A lighter version of what you're saying was implemented in my game 85, with a Mafia role that had unknown characteristics. But there, you could guess based on the very fact that nothing is known about it x)

That is, it's probably not impossible, even intriguing. But you need to think about it carefully.