I cannot seem to add an upstream bug watch for bug #697412 even though the upstream bug tracker exists and seems to me to have the required alias in order for a link to http://debbugs.gnu.org/cgi/bugreport.cgi?bug=7853 to be acceptable. The upstream bug tracker is listed at https://bugs.launchpad.net/bugs/bugtrackers/gnu-debbugs and upon seeing question #141787 I added an alias for /cgi/bugreport.cgi?bug= but still I get an error message "There is 1 error in the data you entered. Please fix it and try again."
(Moreover, this error message is extremely unhelpful. Launchpad should indicate what is wrong or preferably just accept the URL I just gave it. I believe there is an open bug report about the latter alternative, but if it cannot be implemented post haste, the former should definitely be done ASAP.)
So we have another open bug where the 'description' is not scanned for bug links. That said, I've added a comment there and it wasn't picked up, so there is something strange going on for sure.
Separately, we currently only support one instance of the debbugs database (when we wrote our integration code, only Debian used debbugs). We'll need another bug open about the ability to integrate with arbitrary debbugs instances.