Hi. If you know a vet who treats chickens, then that could help. One of my hens was injured by a dog last year, so I can tell you what I did to help her through. I don't know from the photos if your chicken is injured similarly to how mine was, and I do not have experience with injuries from raccoons, but if your chicken's injuries sound like my hen's maybe this will help. I'll copy and paste what I wrote in a different post:
-- When my Ameraucana hen got injured by a dog last summer (deep punctures to both thighs, damaged wing, skin and fat removed from back) she also had loose skin and fat hanging off. Once I had cleaned her and put her in a crate, the loose flesh dried up really close to her living skin. I read that the dead tissue should be removed to help the remaining living tissue not get infected. I wasn't confident cutting off the dead flesh when it was so close to the living, so when she really began to smell, I tried to "jerkify" the dead tissue by giving her a few different rinses with one teaspoon salt in one cup of warm water.
This greatly reduced the smell, and was only needed for a few days. That along with Vetericyn on the outside and tetracycline hydrochloride on the inside to help fight infection helped her make a full recovery. The old dead flesh eventually fell off like giant scabs, and was replaced by good tissue, even the deep muscle punctures.--
My hen did not seem to have bone or internal organ damage, just serious tissue damage, and she survived it. It looks like your chicken's damage is on the belly? How long ago was the attack? Is she eating or drinking? Open wounds and torn flesh, or raw skin with missing feathers? I rinsed my hen with warm water the first night, too, and did try hydrogen peroxide the next day. But after that first treatment, more was needed, and I did what I wrote above. I hope this can help!
Oh. And I imagine that raccoons' mouths can be pretty nasty, so if there are punctures an internal antibiotic might be a good idea! I was recommended tetracycline hydrochloride and so tried it, and my lady didn't seem to suffer from infection.