It would be very helpful for the money that players are spending to go to a specific account, rather than just disappearing.

That's what managed slots are for. Any money that is spent on the managed slot goes into the slot and any money that the slot sends out comes from the slot and not out of thin air. The owners of the slot can then do /casino withdraw name amount to get money from the slot and /casino deposit name amount to put money into the slot.

That make sense?

Makes sense thanks!