I know that hair loss and itching can also be caused by allergies to foods. Too high of a protien diet , is one cause. Also rice can cause allergies in some as well as many oats. Dry skin can also be a cause. Trick is finding the source . Bumblefoot in my experience is tricky. I have a blind lovebird rescue who suffers from it from time to time. Keeping the wounds clean is paramount as well as housing being adequate to prevent reoccuring bouts. I am also a wildlife rehabilitater, and I see bumblefoot in a fee of my patients. One remedy that can work, depending on the bacteria causing the bumblefoot, is Monostat. Its slow to work but is helpful. I use a mild solution of dawn dishsoap, the one with the duckling on it. A soft bristle toorhbrush. Gently scrub the area with soap and rinse. Dry. Rhen apply the cream. With a ratling, it perhaps is best to use a q-tip instead of a brush . More delicate feetsies I think than a raptor.
Very grateful you rescued Cashew! He's beautiful❤