Thank you, @danbp!
I opened the .pot-file finally not with poedit (there I didn’t found any aside-information), rather with an editor. There I got the information, that I can find, e.g., ‘Site-Wide-Activity’ in the buddypress/bp-activity/bp-activity-loader.php.
I changed ‘Site-Wide-Activity’ into ‘Neuigkeiten aus dem 1a-Spielwiese-Netzwerk’ – and it works: 🙂
http://1a-spielwiese.de/activity/
I changed the original file at it’s original place. – Would it work with my child-theme-folder as well? If yes: Where I would have to place my bp-activity-loader.php-Copy?
On the highest level of my child-theme-folder? Inside my buddypress-folder there or inside my buddypress/bp-activity-folder there? Or anywhere else?
