This is to report full success and extend thanks to Peter and Anak.
The hyphenation
in French is now working fine (I can see four words cut on a page where it hardly occurred once).
You'll find enclosed the Kobo uncompress folder I prepared for MobileRead. It includes, the
KoboRoot.tgz file you have to use, and for information purposes only the file
hyph_fr.dic (in lowercase). Once unplugged, the update took place without a hitch on my Kobo Glo 2.8.1.
To use it: unzip and put directly the
KoboRoot.tgz file into your .kobo folder. Once the update has taken place, this file will have disappearred...