It would be great if Bridgy could support publishing an issue with Labels to GitHub, and I think the right way to do this is via tags (e.g. class="p-category"). Note: apparently silo.pub does this.
Example issue: http://tantek.com/2018/061/b1/css-cascade-3-test-suite-not-in-web-platform-tests with tags for labels: css-cascade, css-cascade-3, Needs review of Test Case(s), PR blocker
And the POSSE copy on GitHub: https://github.com/w3c/csswg-drafts/issues/2378 without any of the equivalent labels.
Note: it would be OK if Bridgy Publish to GitHub POSSEd tags only to *existing* labels in the target repo, and not create new tags. cc: @aaronpk.