I made possible discoveries
From The Lost Media Wiki
I know this link (https://archive.org/details/LeManegeEnchantePolluxZebulonMargoteAutresVHS) is on this page multiple times but there have been added episodes that aren't listed here:
2. La chanson de Pollux
3. La chanson de Zébulon
13. Rencontre avec Azalée
14. Zébulon a perdu ses moustaches (NOW IDENTIFIED)
I also possibly found a full episode listing of the 90s series: https://animeguides.com/guides/manegeench89.html
Finally, I found a few mysterious episodes that also aren't listed here: https://picclick.co.uk/WALTON-FILMS-The-Magic-Roundabout-Geography-Game-303701321011.html
One of which is on YouTube: https://www.youtube.com/watch?v=D60cWn68dAY
Feel free to reply, & any criticism and tips are welcome.