Hi @Luis Hernández,
This is quite interesting. For me what differ the tonal practice with the modal practice is that tonal practice has hierarchy of the chords and there are clear functions of them, while in modal practice it will be less hierarchical and the counterpoint and voice leading are the only principle of music, that's why composers will try to have the voices move as smooth as possible, and given the singers at that time are much less professional now the rules tend to be stricter in order to help them sing correctly.
I see in your blog you have said "Therefore, we have a base chord, or tonic chord. Cadential chords (which replace dominant chords) in modal systems are at short distances from the tonic chord. A semitone, a tone, a second or a third, but not a fifth away. Moreover, the cadential chord must contain the characteristic tone (b6). So, we can use several chords as cadential: F7 (bVII), Ebmaj or Ebmaj7+ (bVI), and perhaps Am7b5(ii). The remaining chords can also be used, at the composer's discretion.". Will cadential functions important in the creative scales? In tonal period V chord is the dominant since 1) it's stable in itself (in minor key it's changed to a major V), 2) The fifth is closest note to the tonic as in the overtione series, 3) The use of fifth lower is already commonly used in modal music, like those tuba notes and keys (e.g. hypodorian, hypolydian). If 1) other chords are chosen as the cadential chord, it maybe harder to give audience something stable to be grammatically important. It will have the feeling to be forced upon by the composers to have those notes emphasized. 2) For me the definition of characteristic tone can be freely chosen. Like your key for example I can instead have it interpreted as an upward C melodic minor scale starting on G.
Maybe for me the approach for having two tetrachords instead of an eight-note scale better. You can just decide the tones and semitones inside the tetrachords, as well as tone or semitones between tetrachords. For example if two 0134 set combined with a tone apart, it will be an octatonic scale, but even Stravinsky who is known to used octatonic scales doesn't necessary have those tetrachord in a tone apart, since sometimes he just has them a semitone apart.
Thanks for sharing! That's real interesting.
Henry