As I understand it, even making the edit is violating the copyright. You cannot create a derivative work without permission of the copyright holder. However, making a fan-edit only for yourself would be considered fair-use. But fair-use only means that a copyright violation isn’t prosecuted, not that the violation is nullified.
So, in essence, creating the edit isn’t entirely legal, but also not really illegal. I could have worded that better.
I think fair use is best described as “a legal copyright violation”.