I grow all my Phal violacea var alba in a plastic pot with styrofoam peanut as drainage. I use sphagnum moss around the roots but I soak the moss overnight. Then I squeeze out the excess water from the moss and pack the moss around the seedlings loosely. I also put the seedlings in an area with high humidity and very bright indirect light and keep the temperature high (33 C) during the day and about (20 C) at night. They should recover in about 3 to 6 months. I would also change the moss every 6 months because the moss starts to decay due to moisture.
I think your leaves are probably deprived of water since the leaves are translucent due to root problems and low humidity. My Phal violacea var alba leaves are bright green and very round and thick.