It could be that the frostbite is just on out layer of skin, and not full thickness. We have seen some chickens on here with frostbite on either the top of bottom of the foot, and though some of the skin sloughs off, they don’t lose the toes or foot. I still have hope that the legs and feet will eventually heal. It can take a month for all of the effects on frostbitten feet to show. At this point, maybe the vet will suggest stopping the daily leg baths, and just spraying with vetericyn or just using antibiotic ointment, and letting things heal or not.