The H5MMods folder is not being created for editing index.bin.

Yes, it's visible in the editor, but it's not in the game files.

I see 3 options:
1) The files created by the game are somehow hidden; enable viewing hidden files in the file explorer.
2) The editor cannot create a folder; I've never encountered this, but in theory, you should run it as an administrator.
3) You don't know where the folder is created - in the Editor, and this folder is in the game folder (this is an embarrassing option 🤣).