Thank you for your feedback,
Handling Ctrl-Z and Ctrl-Y isn’t easy because Godot manages them locally in each code editor. I’ve tried combining these local changes with the local undo management, but there may be issues. I’ll take a look at it, but for now, it’s best to limit yourself to one undo and use a second rename to revert to the previous state.
Try version 1.0.13 and let me know if you’re still experiencing issues with the editor freezing.