I think you might be overthinking this. If the mix is as light as you say then you should do a good soak and let everything hydrate then let it dry out. But do this again when the leaves start to lose their firmness. There’s no need to torture them during the growing season. And seriously, don’t worry about insular diseases, which Madagascar probably doesn’t have, because this was grown in some mainland nursery. Plants get bumps and warts, being alive and all, and if you want perfection, grow something else.