Hi there!

As far as I know, there is no other use of those group contributions aside from what you have stated.

Maybe in the future they might add some, who knows. In the mean time, we can just donate and spin lucky wheels. I personally like the lucky wheel :)

In my case, just wanna share this, I always make sure to save those coins/currencies. We'll never know. One day, they are useless, but the next day they are "golds" - must have items. Pretty much the same concept with Space-time betting coins and exchange system.