Hi there,
Actually those warning will shown on all page and not only on emails sections. Those warning are actually for users that set their cache files here
/media/com_easysocial/cache as read only folders.
Currently, i am not sure why it shown to you as un-translated strings as when i trying to check/debug them, i clicked here
https://screencast.com/t/uv8I1gxuOlF Those error no longer shown on your end.
Can you monitor them again and if those problems re-appears, do update us.