Maybe it has or hasn't been addressed yet, I don't want to read through 47+ pages.
But you should also add a limit to how much certain people you trust can withdraw from the bank per day...
example, you give 4 users permission to withdraw, however they can only withdraw let's say, 500 fg per 24 hours.
The guild leader, can of course, set different amounts for different users based on how much he trusts them.
But there should definately be a limit added. This way they can't scam the whole bank.