Lavender and Jasmine flower are added to all my changa blends, they make the smoke smoother and Jasmine in particular compliments the taste of Caapi and spice so nicely.
I also add a bit of Leonitus flower it adds a bit of sweetness to the smoke.
Honestly there's no limit to your imagination, honeysuckle flowers, or even herbal teas can make a great changa, the thing to remember is that harmalas play an important role here. Changa has so much more depth than enhanced leaf, do yourself a favour and get some Caapi leaf or harmalas extracted from vine, or even extract harmalas from rue seeds to add another dimension to your spice experience!
Peace
PW