The "Terrain d'essais de Chalais-Meudon", named on your document was used by the Technical Service from the STAS
(Section Technique de l'Artillerie d'Assaut).
It was the Proving Center for French tanks belonging to the DIEET (Direction des Inventions, des Etudes et des Expériences Techniques) from Jules Louis Breton.
If this kind of camouflage was tested, it was probably only on one Renault FT, and there is no military document from French Military Archives, speaking of Tank's winter camouflage during this war.
I was just surmising that it might have been a form of winter camouflage. Would you say the colours are white over dark earth, or white over dark grey?