I found the name "Acer takisinense" in the catalogue of the "Arboretum des Barres". I didn't find any info on the web on a maple with this name, has anyone heard of it?... Here's the link to their catalogue (they also mention 'Senkaki' as a synonym for 'Osakazuki'...): http://www.arboretumdesbarres.fr/site/medias/Catalogue_vegetaux_ANB_2015.pdf
Well, that seems a very good guess: I'll ask them ;°) This arboretum is about 1 hour from where I live, I've never been there, but I will.
I haven't been either, but it's meant to be very good. Didn't realize it was so close to you. Years ago a friend who is a well known garden designer recommended the quality of the plants available, but I can't speak to it now. They certainly have some other maple names wrong, but that's common enough in France (Acer trifidum, anyone?)