This functionality was’t available until CS-Cart and Multi-Vendor 4.4.1.
Language variables and translations can be added via a theme. Translation files must be located in the langs subdirectory of the theme’s directory and must be named like this:
[language_code].po (for example, en.po).
The language variables of a theme are added to the database when the theme is installed.
You can specify your theme’s default language. It will be used to provide translations for all languages the theme is not translated to. To specify the theme’s default language, use the
default_language field in the theme’s manifest.json:
default_language is specified, there are two possible scenarios:
The store’s default language is determined by the Backend default language setting in Settings → Appearance.