I do NOT think there is any reason to euthanize an animal if they aren't in pain and can function. This definitely needs another vet analysis, but if she is not in pain, I believe you should allow her to learn to adapt to her situation, and it is POSSIBLE she will stop being paralyzed at some point. It happens to humans, I don't know anything about it, but she may slowly recover or suddenly recover. If not, she will probably be able to learn to live this way and still be happy. If she cannot climb you might want a horizontal cage rather than a vertical one, you can put a bunch of diagonal ladders in there and levels which will allow her to climb/drag herself up and get to higher areas. It is a disability, and it does not mean she should be euthanized at all. See how it goes. If it is a bone fracture that is pinching a nerve or something that will probably heal. If her motor neurons are severed from a dog bite or something, they could possibly grow back or may not. I think there is a chance that she could heal from the paralysis, but I don't know. She should be able to adapt to her disability though. Good luck. If she isn't in pain then don't worry about it. Spend time with her and make sure she has her glider buddy.
Ending an animal's life is something that animal has no control over and cannot agree to and thus is NOT a light decision and should only be done if they are in untreatable pain or cannot function. She may heal, the vets don't even know what is wrong. Many causes of this are treatable. Animals can adapt very well to things, please give her a chance. It is possible to have a disabled glider, you just have to change things up a bit to accommodate them. The glider may want to continue living despite this disability.