Yes, it has been tested and works normally in Blender 4.X. If you encounter any errors, make sure you're using the latest version and Blender is an official release.
Yes. The add-on is stable on Blender 4.X and earlier. We continue to maintain it actively. If Blender introduces major changes to the bone naming system, we will release compatible versions. Got feature requests or suggestions? Let us know anytime!