Hi Marco,
Thanks for reporting these issues back to us. We've fixed the issues internally. For the quick fix, download these php files and follow below instruction to apply the fix
1. Download file 'notification.php' and copy the file to 'JOOMLA/administrator/components/com_easysocial/includes/notification/' and overwrite the existing notification.php
2. Download file 'notification.comments.php' and copy the file to folder JOOMLA/media/com_easysocial/apps/group/tasks/hooks/ and overwrite the existing notification.comments.php
3. Download file 'notification.likes.php' and copy the file to 'JOOMLA/media/com_easysocial/apps/group/tasks/hooks/' and overwrite the existing notification.likes.php file.
4. Download file 'tasks.php' and copy the file to JOOMLA/media/com_easysocial/apps/group/tasks/ and overwrite the existing tasks.php file.
5. Add below two new language strings into your EasySocial frontend language file.
APP_GROUP_TASKS_USER_LIKES_THEIR_MILESTONE="%1$s likes their milestone"
APP_GROUP_TASKS_USER_COMMENTED_ON_THEIR_MILESTONE="%1$s posted a comment in their milestone"
Remember to backup the original files first before you overwrite with the updated files.
Let me know if the above fixes work for you or not.
Thanks and have a nice day