Should bastard mechanics be disclosed? I would say yes.
In favor of this sites thing for having nonstop closed setups I think it would be best disclosed in categories.
Break it down something like-
Bastard 1- Mod results may be false because mechanics change them. Things like Tailors or Janitors may exist but were decided pre-game
Bastard 2- OoO may not exist and may be made up on the fly as the host does the game. While there is not an intent to manipulate the game as it goes on the potential exists. Insane modifiers or mechanics may exist on roles that reverse their result
Bastard 3- Your win condition may be changed with functions like a cult or blackmailer placing obligations upon your slot that were decided pre-game
Bastard 4- Core facts of the game such as win conditions or mechanics may flatly be a lie but are decided pre-game
Bastard 5- The host will directly impact and influence the game as they desire after the game has started
Something like this could be healthy to be disclosed. Could probably refine such a list quite a bit as well.