Thanks Emmanuel,
As per
https://forums.modx.com/thread/79164/locale-and-multiple-contexts the solution is to set the language properly in the locale from lexicon and language administration section.
In my case the rigth one is fr_FR.UTF-8.
It was not working properly because I previously set fr_FR.
As an enhancement to modx, it could be better commented in the system admin setup.
I will provide with the site URL for people to understand better as soon as it is online.
Thanks to all the modx league !
Philippe
[ed. note: Fildefer57 last edited this post 11 years, 7 months ago.]