Actually, Armory was interfering with Trinity opening Horadric Caches

I've fixed this in the most recent update to Armory. Not the other way around as you theorize.
I dunno about the other gambling plugins, I don't use them. Trinity doesn't interfere with anything except the root VendorRun decorator (e.g. "when" the bot should townrun, not the actual townrun itself). I think it may be a design problem in the other plugins, as gambling items really has nothing to do with a vendor run, it should/can be executed any time the player is in town. It could even be designed to take a town portal and run the gambling routine should it desire. Again the latest update to armory has a proper implementation of extra hooks a plugin developer could easily re-use.
I will not be adding Kadala / gambling support into Trinity, it doesn't belong it a "combat routine". Trinity is already too complex, bloated and difficult to maintain and understand. God forbid I add more options...