Thanks very much for your helpful reply.
What made me think that Perl/Tk didn't have an active maintainer was that its CPAN page http://search.cpan.org/~ni-s/Tk-804.027/pod/UserGuide.pod said "Nick Ing-Simmons" at the top. I should have looked more carefully. That just indicates that it's still in a directory with his name, not that he's the current maintainer.
I've filed a bug report for the bug in Tk: https://rt.cpan.org/Public/Bug/Display.html?id=82203