Hi sorry to tell you but in my experience with bad sunburn the leaves will die. However if its a plant you really want to keep withhold watering after the leaves fall off. Water very very sparsely barely enough to dampen the surface. The goal is to keep the roots alive even after you feel all is lost. Keep checking the roots to make sure they are still alive. After a couple of months the plant may recover with a basal keiki. I too have struggled with phals they normally die because the moss held too much water. Now I remove 3/4 of the moss and leave the inside ball. I then fill the pot with styrofoam and water once a week. This has worked for me hope you find a technique for you area