Thanks, Alex!

I have reached out to The Open Group via some contact form on their website; 
let's see if I'll get a reply from them.

On Wednesday, 28 September 2022 15:56:29 CEST Alejandro Colomar wrote:
> The person who could clarify this certainly is Michael Kerrisk.  I'm not 
> sure if he will have the time to read this, though.
> 
> I'm sorry I have no idea.  POSIX is too closed for my taste.  I tried 
> contacting them a long time ago regarding this, and I received no 
> answer, and their website is a labyrinth to me.
> 
> I encourage you to try to contact them with this problem, and ask that 
> they clarify it, and if possible, that they publish the source code 
> (hopefully the roff(7), not HTML) with whatever license they wish, so 
> that I can pick it easily.  I'm worried that if they don't do, I won't 
> be able to provide manual pages for the next revision of POSIX, if they 
> don't.
Hmm, that's a rather unsatisfying overall situation indeed. The description in
https://git.kernel.org/pub/scm/docs/man-pages/man-pages-posix.git/tree/README
is also vague on the details of how and where exactly to obtain the troff 
sources.

I'd really like to get back to a state where I can successfully type
`man pthread_cond_wait` into a terminal on Fedora.

Best,
Christoph