Good catch! This issue is related to the site setting site_contact_username and site_contact_group_name — when either are set, they’re who would be included on these messages. But when they’re not, it falls back to system, which is a dead end if no one is monitoring it.
The simplest thing to do would not include that info about the reply in the case when a contact isn’t set.
So when a contact user/group is set it says:
You can edit your original post below and re-submit to make the suggested changes, or reply to this message if you have any questions.
And when one’s not set, it’s just:
You can edit your original post below and re-submit to make the suggested changes.