Special:WithoutInterwiki should be updated to handle pages that has no own interlanguage links but are referenced through sitelinks. The special page identifies pages that does not belong to any interlanguage cluster and should work.
A possible variation would be to change the existing page to handle both ordinary links and links published from the repository. In this case it is important to show pages that are missing links from the repository, as that will be pages that still isn't processed.
Version: unspecified
Severity: enhancement
See Also:
https://bugzilla.wikimedia.org/show_bug.cgi?id=41038
https://bugzilla.wikimedia.org/show_bug.cgi?id=41044