Hi @wlaurito-
The Deutsch language file (in languages/bp-docs-de_DE.mo) is missing some strings. I’ve updated the de_DE.po file to include the new strings here:
https://github.com/dcavins/buddypress-docs/blob/de_DE-translation-update/languages/buddypress-docs-de_DE.po
If you can translate the rest of the strings using PoEdit or similar, and put it in your languages directory (make sure the names of the new .mo and .po files match the current names), the translations should take effect.
Read more about creating language files: https://codex.buddypress.org/getting-started/customizing/customizing-labels-messages-and-urls/
The next version of BP Docs will take advantage of the WordPress online translation community, so hopefully language files will be less of a problem.
Best,
-David
p.s. also note that newer versions of WordPress ignore the WPLANG
constant and use the selection made in your sites Settings > General screen.