Jean203, I found tons errors in your translation!
First, you forgot the very important thing: opening tag before the tutorail translations:
// List of default (English) text strings and their translations.
ScriptTranslations
{
Without this, tutorial translations simply will not work! Did you ever tested them in SE?
Second, you didn't translated the menu strings. Look the rus-gui.cfg, they are typed before tutorials in the same ScriptTranslations { } section.
Third, you can't use double quote " inside the string. The double quote is a string delimiter. You translated string is ended at cliquez sur, and after the quote you got a syntax error. You can use a single quote ' instead.
"You may share the selected location by clicking the Share button. Currently available options include copying the code of the location to the clipboard. You may later paste it to the web forum or messenger." "Pour partager l'emplacement sélectionné, cliquez sur "Partager" et sélectionnez "Copier l'URL dans le Presse-papiers". Ensuite, vous pourrez ensuite coller le code dans un forum Web ou une messagerie."
Always inspect the system/se.log file for any possible errors:
[MT] Loading script "data/locale/fra-gui.cfg"
[MT] "data/locale/fra-gui.cfg" line 1483: ERROR: Syntax error ''URL'
[MT] "data/locale/fra-gui.cfg" line 1486: ERROR: Syntax error ':'
[MT] "data/locale/fra-gui.cfg" line 1486: ERROR: Syntax error 'йpart'
[MT] "data/locale/fra-gui.cfg" line 1578: ERROR: Syntax error 'йan'
[MT] "data/locale/fra-gui.cfg" line 1594: ERROR: Syntax error 'йfaut"."'
[MT] WARNING: seStringStorage::SetLocalization(): GenderPlanet parameter not found
[MT] WARNING: seStringStorage::SetLocalization(): GenderAquaria parameter not found
[MT] 1277 localization strings loaded
[MT] WARNING: loc.SetLocalization(): Translation not found for some strings:
--------------------
"Stellar barycenter"
"Planetary barycenter"
"Planetary barycenters"
"Asteroidal barycenter"
"Spacecraft#plural"
"Structure"
"Artifact"
"Constellation"
"Waypoint"
Fourth, the latter is a list of untranslated strings in the log file. If they are translated, this error may be caused by forgotten " (or one extra "). If they were not translated, you may simply copy them from the log file to the localization file and add translation.
By the way, locations from the F6 menu name probably should not be translated (example: Pluton : départ de la sonde Nouveaux Horizons). They are displayed in English to everyone, and this will confuse players.
I see you have a mix of double quotes, single quotes and angular quotes ( « tempérée » ), and redundant spaces. Is this a pure google translation?