The tag is present in Lintian version 2.104.264. That is the most recent version we know about.
Even though this package provides debconf translation support, there are no translations or none of the translations are complete. This may mean that translators weren't properly warned about new strings.
Translators may be notified of changes using podebconf-report-po, for example:
podebconf-report-po --call --withtranslators --deadline="+10 days" \ --languageteam
Refer to Debian Developer's Reference section 18.104.22.168 for details.