The result is pure hell for anyone trying to interpret the mess with
anything but groff itself. I believe I am the only person who has
even tried this seriously.
I managed to handle almost all of it, because I am exceptionally good
at the kind of hacking required for the job. But not in fact all of it;
it's one of the major sources of the tiny percentage of pages that
doclifter chokes on and that cannot be fix-patched.
The effort required to get this far with mdoc was extreme even for
me. Thus I consider that effort very unlikely to be successfully
replicated - I doubt anyone else will have the stamina required.