Maybe it was a fluke then, but I was noticing my HP going up while using my hellfire in a hunter round. I never hit the hunter with them, I had like 68 damage from hellfire flame. But I shot a player and hit him with the Djinn ball and it healed me. Definitely didn't trigger from the hunter, since it pops up if you damage him. Probably easy to test, albeit hunter rounds are so scarce.
Can verify they do work in dragon rounds though
Just tested it in another Hunter round, definitely works. I was healing fast as heck.