@wawa79 So while answering a similar question for the Spanish language, I was able to get it working for the French language as well. It appears that you have to formulate the request a certain way.
If you label your item as Salon Volet, the below utterances are working.
Rollershutter AX_DW_mRDC_Salon_volettest "Salon Volet" {alexa="RangeController.rangeValue" [category="EXTERIOR_BLIND", supportedRange="0:100:10", unitOfMeasure="Percent", actionMappings="Close=0,Open=100,Lower=(-10),Raise=(+10)", stateMappings="Closed=0,Open=1:100"]}
“Alexa, ouvre le volet du salon”
“Alexa, ferme le volet du salon”