Been doing research on CAG, problems and solutions.
African Greys and other parrots can definitely be rehabilitated if allowed to move at their own speed.
be.chewy.com
This is one of the many articles that they have written about CAG. They have articles that cover fear of leaving cage, being handled and more. They also suggest solutions. I've read several articles of theirs. You can use these as a baseline. Remember to use a grain of caution. Behavior is hard to define in a CAG and all pet birds. They are prey animals. This is their basline period! I sympathize with you. Do as much reading as possible on different sites. Use this forum as a backup. Think of outside reading as objective thinking. It's what the book says should have a chance of working. Think of this and other forums as subjective thinking. It's what I and others independently discovered what works for us.