Music Composers Unite!
I am fascinated by your absolute rejection of "atonal". I agree that it is kind of a "catch-all" term. Yet so is "classical", for that matter.
As an American English speaker (not to be confused with British English), and in possession of a Music Ed degree, I have never heard of "thesis" and "arsis" as musical terms.
We all know that English is not a pure language, by any means. It is made up of so many different languages that we can't treat it like your Greek. Nor should we. So many words have, as you say, the opposite meaning now than they did a few short hundred years ago. To which I say "so what". That doesn't mean that I don't take language seriously. But I don't get to decide what words mean.
Then there are words that even the dictionary can't define. While performing in a Shakespeare production, I looked up the word "anon".
1. now, straight away.
2. soon, presently.
3. later, sometime.
Or it was an inside joke. The character was saying " Yes, I will be there.....anon" What he meant was "Yeah, right. see ya".
Just some thoughts.
On further thoughts, I wonder if pitch contours can be classified into a number of basic categories, like basic shapes that could serve as building blocks for constructing a larger glide melody.
Basically, in the context of glide music, there's not much difference between a glide from C up to G, say, vs. from C up to A#. The basic shape is the rising pitch. Of course, a more extreme difference could be perceived differently, so one could distinguish between a narrow glide like C to D vs. a wide glide like C to C an octave above.
Similarly, the descending glide also serves as a distinct gesture, and an upglide followed immediately by a downglide serves as an inverted V shape gesture. Its inverse, the V shaped glide, can also be another basic gesture.
Also, while absolute pitch is not important, one could arguably distinguish between a generic high pitch range and low pitch range, so a rising gesture can either start high or start low, and that could be treated as a separate gesture. Similarly for the other basic gestures.
So then this gives us a "vocabulary" of basic gestures, like high rising, high falling, low rising, low falling, with wide/narrow variants thereof, and the high V, low V, high inverted V, low inverted V, also with wide/narrow variants. We could then treat these gestures as "letters" from which we can "spell" glide contours, forming "words" (motifs) which can then be assembled into phrases and sentences. Phrasing can be done by structuring the rhythms of the gestures appropriately.
Then pit two voices together and you have some basic counterpoint. You could then construct a "glide fugue" out of multiple voices. :-D