Ah, thank you, that watch line you listed seems to work properly. I uploaded this change to mentors now, and it seems to pass without any warnings.
You're welcome. :)
I'm not thoroughly review your package but it seems that you bump the standard-versions in this upload to mentors.d.n without any logging in debian/changelog.
Hopefully, you already consult /usr/share/doc/debian-policy/upgrading-checklist.txt.gz and no changes needed.