On Mac, apps would follow to system language, or you may set a language per app (if an app has built-in support for that language: menus, functions, navigation, headers, etc.). Change the language your Mac uses - Apple Support
Some graphics with text may still use the main language of your region. Images do not have language versions within each region.
Descriptions may not always be available in multiple languages, and rarely in the 4th language of the country.
The app language sets the preferred audio language (if available in the stream). English may not always be included; sometimes you only get a dubbed version; that varies by title and by country or region. See the Store page for included audio languages and subtitle languages. Language support for content is ultimately a studio decision, per country or region.