If there could be a way to create a tag for the tickets that have no tag, so - for example - a broad auto-reply automation could be applied for the untagged tickets to confirm receipt of the email/reply-time estimate, etc.

Ideally, being able to have all auto reply automations live in Lang, so you do not need to worry about two auto replies triggering (if you had one in ZD AND one in Lang, which wouldn't be an ideal user experience).