1, Subscriber multiplier
This was a feature that was present in many other loyalty systems such as Revlo and StreamElements, you already have a donation incentive in place, I see no reason not to include this.
2, Cooldown settings for the minigames
Some people can be trigger happy about their gambling and lose everything in a few seconds/minutes. It would be nice to have an option to add a cooldown to the card/scratcher minigames.
3, Randomized spawn interval for chests
Currently it's on an exact timer, and people are setting up stopwatch timers to be ready anytime there is a spawn. A slight randomizer (spawns between 5-10 minutes or something similar) could alleviate this problem.
4, Multiple tiers of chests
The chest system is awesome, but if could be further customized by having multiple tiers of them. Adding some SUPER rare chest that only shows to 10% of the viewers every hour, and/or a more common one that's very frequent to keep people engaged would be cool.
Currently only the broadcaster can see how people stand, and people were asking about a leaderboard, or ability to check how many things other people have.
6, Dueling - PVP
Ability for people to put up bets against eachother and have a cointoss. I'm sure you know about this feature, it's been present in many other platforms.
7, Community goals
Much like a doantion goal, we could have community-loyalty-point-goals where people could "donate" their stream currency points towards a bigger pool, like having the streamer play a particular game on stream, or otherwise influence the content and make it more interactive.
8, Ability for the streamer to award points to one, or all users
Let's say something big happens on stream, so the streamer says everyone currently in stream will receive X currency. Or let's say the streamer asks a question and says whoever answers it correctly first gets awarded X currecy.