The key signature meta-event is barely functional if you have a remotely expansive view of "music theory". Identifying a root note, major/minor and number of sharps OR flats doesn't really pin down a large number of actual scales.
For your purposes, it may be enough, but in more general terms, it's woefully underspecified.
A better way for MIDI to have done this would have been to use a "standard" scale numbering system combined with a tonicity count. An example or two is given here:
I appreciate that your current project doesn't need this, but if someone wanted to somehow create a MIDI file that included the information "this uses Locrian with a flat second", the current SMF spec is inadequate.
Absolutely, midi is clearly a device centric protocol, not a musically correct protocol. But with the various XML music formats there are alternatives that can be converted into midi fairly easily. But right now we only support midi, we will add more formats though.
For your purposes, it may be enough, but in more general terms, it's woefully underspecified.
A better way for MIDI to have done this would have been to use a "standard" scale numbering system combined with a tonicity count. An example or two is given here:
https://ianring.com/musictheory/scales/
I appreciate that your current project doesn't need this, but if someone wanted to somehow create a MIDI file that included the information "this uses Locrian with a flat second", the current SMF spec is inadequate.