Translation: Still english after setting $locate=”de_DE”

Hi
Following your documentation I did set $locale to “de_DE” as described. After deleting all caches text such as “You also might be interested in” after a post is still written in english instead in german.

The suggested plugin “Codestyling Localization” is no longer supported.
Do you have any advise?

Thanks in advance.
Best regards,
Philippe