Resolved. Fault is on my part, i extracted the entire directory and not just mmd_tools into the addons Blender folder. For whoever has the same issue, the README.md's Usage sections contains your ...

Python: Traceback (most recent call last): File "C:\\Program Files\\Blender Foundation\\Blender 2.93\\2.93\\scripts\\addons\\cats-blender-plugin-master\\tools ...