She will be beautiful again, it just takes lots of time and patience. My girl ate neosoprin without the pain relief, every time I put it on her and It never had a negative effect on her. I even checked BYC to see if it was safe to eat. No one had anything negative to say. My girl was so bad off, I figured I had only something to gain by trying. I would keep using Neosporin to promote granulation in that open area on your hen. I also have new feathers coming back on her thigh, as the skin continues to cover more and more of the thigh. The gashes have healed for the most part. I filled them with Neosporin as well.
Good luck with your girl, Chickens are smart and resilient animals, and it sounds like she has gotten great care from you. Sit back, continue what you have been doing and pat yourself on the back for saving your hen. You have done a great job as far as I can see.