Wow. What a story. So glad they're in your care, and my heart breaks for the other chinchillas and what their condition must be.... Ugh. But to take this to a lighter note, I, too, adopted a very severe fur-chewer. She actually looked a lot worse than those pics you posted - almost as if she'd been shaved - everywhere she could reach. We didn't know if it was an illness or what (didn't know much back then).
I fostered her from the shelter because she obviously was in no condition to be adoptable at that point (for many reasons, fur-chewing just being one). Obviously she ended up with me. Point of all this is, though, that while she came to me nearly bald and acting neurotic or aggressive, she became a well-adjusted and happy chinchilla who not only grew back ALL of her beautiful jet-black fur, but also developed a wonderful and trusting friendship with me. I feel so lucky to have had her in my life.
Sounds like you're off to a good start with these poor chinnies, especially as they already respond to you positively. I'm sure better health and habits will follow! Please do keep us all posted, will you?