Wood is right that it is not working correctly. The python script never extracts the mission and theatre files from the miz file. Fixed by adding these lines that I would guess were present at some point back into the script.
extract_mission_file(G.s_mission_miz_path, G.s_mission_miz_filename, 'mission')
extract_mission_file(G.s_mission_miz_path, G.s_mission_miz_filename, 'theatre')