"Sweet Chorus" is kinda a mash up of an 1930s 8-bar blues melody, and a mysterious and atmospheric miniature composition by a French Impressionist composer like Debussy or Ravel.
Chromatically ascending chords
Bars 5-6 of the A section form feature an iconic Django compositional tool, which is a chord shape which moves chromatically. In this case it's a dominant 7 chord which goes Eb7, E7, F7. I'll explain the best way to play this movement in the left hand, as well as ideas for chord voicings in the right hand, and ideas for improvisation over this section.
Mysterious sounds from the whole tone scale
The wonderful introduction, and most of the V chords in this song feature heavy use of harmonies and melodies derived from the whole tone scale. I'll show you my suggested chord voicings to match the sound of Django's Quintette, as well as a few wonderful whole tone scale patterns for improvisation over those measures.
Bending notes and tremelo
Django's style in this recording features heavy use of bends and fast tremelos on melody notes (think mandolin style). These are very guitaristic, but quite challenging and unusual on the accordion. BUT NOT IMPOSSIBLE. I cannot perform these techniques on this melody, YET, but I want to share my method that I'm going to use to teach my nervous system to do these things in a controlled and repeated way (like adding words to my vocabulary.) I think you'll find this inspiring for you.
The Cycle
I champion practicing in a cycle or exercises around a song. Starting gentle and warming the nervous system and musical creativity up, and alternating specific etudes (exercises) to build nervous system movements, and playing the same elements with spontaneous creation (improvising).
Crucial: You must maintain bellowing out 2 bars and in 2 bars for all of these exercises. You will see how much this seemingly remedial and overly simple concept helps your technique in many ways.
Order of work:
BELLOWS: 2 bars open, 2 bars closed
Left hand alone (play through the chord changes with Frank Marocco short quarter notes. In time, nice light and short, great feeling. Bellows out 2, in 2.)
LH + RH melody
Right hand alone, quarter note chords (just like step 1).
LH + Right hand, both hands playing chords in quarter notes.
LH + Right hand, keep left hand on quarter notes, right hand plays same chord shapes but create syncopation against the left hand.
LH + Right hand soloing on the roots of the chords
Hands together, Jazz Sandwich: play melody, take a solo, play melody
Thanks for writing out the exercise in detailed steps. I haven’t done much with the syncpated chord shapes in the right hand but it seems a good way to even approach the melody. I could see using it as a chorus in the jazz sandwich.