hello jan! ,
Sorry for late reply to this,
I have tried to access in your FTP, but it seems like when i rename the this folder com_easysocial and access in your Easysocial dashboard page, it will not get affected, it look like I'm not open the correct file.
By the way, can you remove it this 2 language file?
JoomlaFOlder/administrator/languages/select your language/xx-XX.plg_app_user_blog.ini
JoomlaFolder/administrator/languages/select your language/xx-XX.plg_app_user_blog.ini
because we have move all the apps language in xx-XX.com_easysocial.ini
By default you no need to manually do the translation for this. After you removed, it will display your current language. Please have a try.