1. Thanks for the link. I am reading a bit of your code right now :) Also nice to see that it is GPL licensed too. In regards to intervals: What still confuses me in the design process is that in certain uneven tunings, (e.g. Pythagorean) there seems to be two approaches to naming intervals. One would be an "absolute" approach, where intervals that do not form a 5/4 ratio would not be considered a major third, and one "functional" approach, where the exact frequency ratio does not matter and the interval name is simply deduced from the note names (D to F# is a major third even tough the ratio is 81/64)

2. I'm not sure what you exactly mean by sub-scales. Imho the best approach in xenharmlib to define maqams from ajnas would be to define ajnas as interval sequences in 24-EDO and then concatenate them with + to a maqam interval sequences. Then you can use the result to define maqams on any note.

3. Thanks for the links. I will add something soon ;) I also tried my luck on the MEI Slack channel but did not receive any response. I think MusicXML might be a good format for exporting xenharmonic data, but importing from it is tricky. In certain temperaments the cent values have so many digits after the point that importing would be forced to apply heuristics for rounding errors :/

4. Option a) is currently the one I use, but I am somewhat unhappy about it, because it requires a "tacit" understanding between two programs of how exactly the 128 notes are redefined (also 128 is not plenty, just think of turkish makam that has 53 notes per octave. That is barely 2 octaves in this system). My hopes are currently on MIDI 2.