hello Marco,
Sorry for late reply to this,
Can you try apply this language string in your
JoomlaFolder\language\en-GB\en-GB.com_easysocial.ini and see how it goes?
APP_EVENT_PHOTOS_NOTIFICATIONS_COMMENTED_ON_USERS_PROFILE_COVER="%1$s posted a comment on user profile cover"
APP_EVENT_PHOTOS_NOTIFICATIONS_LIKES_USERS_PROFILE_COVER_SINGULAR="%1s likes {b}%2$s's{/b} cover photo"
APP_EVENT_PHOTOS_NOTIFICATIONS_LIKES_USERS_PROFILE_COVER_PLURAL="%1$s likes your event cover"
APP_EVENT_STORY_USER_SHARED_FILE_IN_EVENT="$1$s shared a file in the event %2$s."
APP_EVENT_PHOTOS_EMAILS_COMMENT_PHOTO_INVOLVED_SUBJECT="{actor} comment your photo"
APP_EVENT_PHOTOS_EMAILS_COMMENT_PHOTO_INVOLVED_HEADING="%1$s posted a comment on your photo"
APP_EVENT_PHOTOS_EMAILS_COMMENT_PHOTO_INVOLVED_CONTENT="This is a notification to inform you that %1$s posted a comment on your photo."
APP_EVENT_PHOTOS_EMAILS_LIKE_PHOTO_INVOLVED_SUBJECT="{actor} likes your photo"
APP_EVENT_PHOTOS_EMAILS_LIKE_PHOTO_INVOLVED_HEADING="%1$s likes your photo"
APP_EVENT_PHOTOS_EMAILS_LIKE_PHOTO_INVOLVED_CONTENT="This is a notification to inform you that %1$s like your photo."
If still the same, can you provide us with your Joomla backend and FTP access so we can check on this missing language string issues?