As for immortality, someone living on an island where times moves slowly would seem slow-again or immortal to the rest of the world, so the only real discrepancy is probably Exoristos--and, though I liked Demon Knights, ignoring a small point about a short-lived series that happened at the beginning of the New 52 could be an acceptable discrepancy. But, if they really want to rationalize it, they could say that Exoristos' body, having long been nurtured in a place where time moves slowly, continued to age slowly, even imperceptibly, for a long time after she left the island. Eventually, her body might have adjusted to the pace of normal time and aged and died. (We don't know what eventually happened to her, do we?)