Font Search Path works for config.ini files as well as sounds.
So if you put your global parameters in a config.ini file in a common folder, they will be used if no config.ini is in the font itself, and will be ignored/overridden by having a config.ini upstream in the font as usual, so it can be either; per-font based or global.
That said, I suppose it wouldn’t be impossible to have a dedicated config file for the screen in the future. Some code that includes stuff like:
FontOledConfigFile font_oled_config;.
and then do
font_oled_config.ReadInCurrentDir("oledconfig.ini");
to get the parameters? (or maybe “screenconfig” is a better nomenclature?)
That would break the all-or-nothing use of the font config.ini for both audio and display settings, and then the OLED settings could be global while allowing the audio to still be set on a per-font basis.