So I just went down the rabbit hole of reading the poisons standard, and you’re right, ibogaine is schedule 4.
From my understanding, sananga is not made from tabernathe iboga, but from tabernaemontana undulata. Same family, but different genus. It looks like they share a bunch of alkaloids, but I can’t find a definitive answer about ibogaine being an active in sananga. I wonder if it would fall into a grey area because of this?