The filament files inherit from other files, which inherit from other files and there the material might be defined. So "None" is the most common material name...
When looking up the material name, it should also load the inherited files all the way until the file doesn't inherit anymore or the material entry is found.
This will need a second argument with the system dir as well.
The path to the filaments might also be something else than "default". The OrcaSlicer.conf "preset_folder" key says which dir to use.