Modifying those global variables does nothing..
I have resolved my problem by reconfiguring the Debian's "locales" package
# dpkg-reconfigure locales
And then i selected the default locale "fr_FR@euro"
After a reboot, many programs were in French, i had all special french characters available in the Konsole and also in java applets ^^
Why i didn't try this earlier?
Because, when i installed the "locales" package, i had already selected "fr_FR@euro"... why it hadn't be saved? i dunno.
Now I have a problem with fonts :/ In many dialog boxes, they are about 6pt..
Anyway, Thanks for you help.