I don't really understand what you mean by without having to modify the Tags. Do you mean that you want to trigger Notifications without modifying the trigger tag? By the way, the latest release of Notifications is 2017 (18.104.22.16865). Have you considered upgrading?
Check this out.
Example 3. Using PI Notifications to check for data freshness
It mentions how to monitor stale tag. Stale means there is no update for tags. I believe stale contains Comm fail too.
You can monitor it by PI Notificaiton 2012 too.
Retrieving data ...