Together We Rule isn't out yet officially, but I've been playing through it on the beta branch. A big problem with leverage is the usefulness of it early game. You only have placate unlocked to lower war support. I found that either A) I wasn't really fighting against an empire, so I was just collecting leverage for diplomatic stars. B) The empires I was fighting against I wanted their territory, so I didn't really care about lowering war support.

I have yet to test the other features, but this just leads to a number being collected that I'm not really using for a significant portion of the game. If there was a way to use leverage to purchase trade goods this would vastly increase the usefulness. This fits the playstyle of diplomatic factions, narratively I think leverage for goods could be justified as contracts that open up and deals being struck, mechanically this could really open up a playstyle.