Leave as is, I think it's fine! I have watched black roots begin to sprout new green roots when the plant gets settled into its new pot. I think it will be just fine now that it's in breathable bark. I do mist my aerial roots daily ... I figure it can't hurt, right? This way if I ever wait too long between waterings/soakings, I know it's at least gotten some moisture from the mistings, and won't get too shocked.

Like said earlier it does look like sunburn. We need more information about the plant to be positive on that though. How big is the plant? Does any of the other leaves have this issue? Do you have hard water? How much sun is the plant getting? What state/Hardness zone do you live in. Keep in mind plant leaves don’t last forever and some may fall of as a plants natural way of “Pruning” itself.

The question isn't whether or not the propagule will form roots ..... it has a large adventitious root already attached. If the propagule includes a node (it appears it does), it is capable of producing a complete plant. If it doesn't include a node, it can only produce a plant if the species is capable of de novo regeneration. Though it doesn't look like it's simply a leaf cutting, I can't see what's in the bottle. Something I wrote about the topic: Cuttings (leaf) Many plants can be propagated from leaf cuttings. The pivotal point is whether or not the propagule is capable of forming adventitious buds. Some plants have groups of cells that descend directly from embryonic cells engaged in meristematic activity. These cell groups can differentiate into buds/shoots from foliar embryos that formed as the leaf was forming. More commonly though, wound-induced secondary meristems can form when existing tissues already acting as part of an organ dedifferentiate into NEW meristematic regions (de novo regeneration), then redifferentiate into new organs (buds). If you want to be fairly certain that you'll be successful in your cloning attempts, make sure you include a latent or actively growing axillary bud, which would be located just distal to (above) where the leaf is attached to the stem. The downside to propagating from stem cuttings with a singular leaf in water is that often the bud is destroyed by rot, and/or, the type of root tissue that forms in water is physiologically very different from root tissue that forms in a solid, well-aerated medium. This difference is made manifest in the water-formed roots being very poor at taking up water from a solid medium, along with the fact that water roots are very delicate, almost brittle. As such, they handle the transition from water to soil poorly. Many leaf cuttings will readily produce roots to form 'blind cuttings', which means they are incapable of forming the adventitious buds which are prerequisite to shoot formation. I don't know if your plant is one such, but if it lives on and on w/o forming a stem, you'll at least know the reason. To reiterate, it's best to bring an existing bud along for the ride or be ready for a disappointment. Blind cuttings can live for years, but eventually they collapse for no conspicuous reason. Al

A lot to take in there Tony. Your post was 11 days ago and no one answered, what's going on with the cuttings now? Don't worry about leaves, sometimes they're a detriment and require too much moisture that the stem can't provide, even with a small root system. There's enough energy in a leafless stem to produce a plant from the node if it's in good shape and in good conditions. Personally I would stay with sphagnum moss unless leaves get droopy, then rehydrate in water and either leave it there or go back to moss and put in a closed atmosphere... a plastic bag or terrarium/aquarium. You might get away without bagging if you cut off a leaf to lighten the moisture load required by the stem. I think the stem blackening will occur no matter the medium, so don't go back and forth between mediums. Moss has a natural rot-inhibiting characteristic, so many prefer it to soil mediums. It's also hard to overwater since it's a loose material, I often scrub perlite into it to make it even more open. Again, how are things looking now?