After hearing Saint-Martin's improvisations from Editions Studio SM (1956) I decided to attempt at transcribing them, as no one has since they were first published in 1956. The recordings were in mono and are obviously lower quality than recordings these days, so the task was not all that easy. I have published the works on IMSLP, so far Improvisation pour l'élévation and Improvisation Libre. I most certainly never took any classes at transcription or the like, but I hope these scores may still provide a useful and accurate as possible.
The scores:
Improvisation pour l'élévation
"https://imslp.org/wiki/Improvisation_pour_l'élévation_(Saint-Martin%2C_Léonce_de)"
Improvisation Libre
"https://imslp.org/wiki/Improvisation_Libre_(Saint-Martin%2C_Léonce_de)"
or
https://organareginaecaeli.wordpress.com/sheet-music/(Under transcriptions)
Audio Samples available here:
Improvisation Libre
http://www.contrebombarde.com/concerthall/music/36265Improvisation pour l'élévation
http://www.contrebombarde.com/concerthall/music/36254