I'm also having issues.. just installed http://mirror.slitaz.org/iso/4.0/slitaz-4.0.iso with
fr_FR language and fr azerty keybord. Noticed once booted up that I couldn't seem to get gparted, so went to a terminal and noticed locale problems... BTW what seems to workaround this is '# LC_ALL=C gparted'
what's strange is that /usr/share/i18n/locales contains fr_FR and fr_FR@euro
and if I change try
$ LANG=fr_FR@euro LC_ALL=fr_FR@euro locale
seems to work okay!
1. It would be nice to update the install-time screen to add the euro locales
and still
2. fix so the base locales work
fwiw