Shouldn't the bank run out of money at some point then as the money to change confession goes to the treasury which is kept seperate from the bank?
1. The rule book I have does not specify what to do if the bank runs out, but does state that the general actions are always available, telling me that should the bank run out you are to substitute some other tokens.
2. Even if you choose not to honor point one, players could continue to hold out indefinitely claiming to have the Ambassador/Inquisitor. As they neither gain nor lose money in this claim and remain in the 7-9 coin gray area. Only the immediate next player has any incentive to challenge as if they win the challenge, they launch a coup the next turn. But if they lose they become kingmaker.