I can help with the investigation part. This is what you are looking for:
https://www.godowsky.com/Compose/anthologies.htmlThese are not it:
Airs of the Eighteenth Century 1. Exaudet's minuet - 2. Lisette - 3. La mère bontemps - 4. Maman, dites-moi - 5. Bergère légère - 6. Pergolesi: Que ne suis-je la fougère - 7. Venez, agréable printemps April 3, 1937 G. S.
These are:
Renaissance, Free Transcriptions of Old Master Pieces
Book I - Jean Philippe Rameau
1. Sarabande, E major - 2. Rigaudon, E major - 3. Menuet, A minor - 4. Menuet, G minor-major - 5. Elegie (on two gigues), E minor - 6. Tambourin, E minor December 28, 1906 S. B. M.
Book II
7. Johann Schobert: Menuet, E-flat major - 8. Arcangelo Corelli: Pastorale (Angelus), G major - 9. Jean-Baptiste Lully: Sarabande, E minor - 10. Jean-Baptiste Lully: Courante, E minor - 11. François Dandrieu: Capriccio (Le Caquet), E major - 12. Jean-Baptiste Loeillet: Gigue, E major December 28, 1906
Book III - Jean-Philippe Rameau
13. Sarabande, A minor April 28, 1909
14. Musette en Rondeau, E major - 15. Gavotte, A minor-major April 22, 1909
16. - 18. (unpub.)
Book IV
19. Domenico Scarlatti: Concert-Allegro, A major February 8, 1909
20. - 24. (unpub.)
As with the Chopin-Godowsky etudes, some stuff is either lost, never composed or never published.