i managed to fix the warning about “this project does not have localization data (translations) for this culture” by adding this line in the DefaultGame.ini
[]
[Internationalization]
+LocalizationPaths=%GAMEDIR%Content/Localization/NewTarget
[/]
i can now find in “Show Localized” english and français !!
i thought that would fix the localization missing in packaged game but no 
i still have no translation working in my packaged game
there is no folder “localization” in “Saved\Cooked.…\Content” path
is there a manual line to write somewhere that i forgot ? :o