Still watching this, but had to say that the boys are right: multiple currencies are clumsy and make the game less interesting to play by removing player choice about how to spend one's earnings.
Just echoing what others have already said: What a great idea for a feature! Mahjong is a game I've known of for decades and still know almost nothing about. Keep it up, GB!
The rules DO make a game fun, because they put everyone on the same page and focus competition/cooperation onto specific skills. Winning ain't the only thing; heck, it may not even be the point.
Capstan's comments