Good News!

Although Wolfram hasn't advertised it, it looks like the formatting on Symbol pages was fixed in 13.1. The info button on the symbol hover drop-down is still squirrely, but it's livable with the workaround above. I had to rebuild some pages, since:

1. Metadata fields have changed (it's simplified)
2. Metadata has moved to the bottom of the Custom Function, Reference, Tech Note page template.
3. Tutorials are now officially, and consistently, Tech Notes in all reference fields (but still stored in the Tutorials subdirectory of the paclet documentation).

Most of this was just a copy and paste from my old pages in the old format, which didn't build well. Now, I can't tell the difference between my custom symbol pages and Wolfram's.

I'm having similar success and the built documentation very nearly matches the 12+ Documentation Center formatting. This is a HUGE step forward.

Note that the new PacletBuild performs the PacletDocumentationBuild + CreatePacletArchive all in on step.