Yes, Iunna did become an Immortal. I think she was one of those that went past Avatar but still lacked a religion. She did a lot in watching over the Heralds as an Immortal, but one day she just vanished. As far as I know, she hasn't been seen again. She disappeared about a month or two before Bria did the same, I think. My sense of time has always been a little hard to keep intact.