Pretty easy for these types of corals to survive, even after some necrosis. I doubt air bubbles where the cause unless it had been trapped under the crown for a good period of time but still a definate possibility.
Being sure the affected area is cleaned away is a good first step but you should also do a couple of sizable water changes using well aged SW
with matching parameters. You need to ensure the DOC
is a s low as possible to help starve any bacteria affecting the coral. Adding a good marine vitamin to the water high in vitamin C will also help. Just use twice the amount recommended on the bottle. Remove any carbon/resin products if you do though as they will remove the additive.
As long as the leather does not continue to be irritated, you keep the affected area clean of necrosis and the water quality specs are kept in good order; the leather should recover just fine. Don't be suprised if the leather also slough's for a short time.