Hi David,
from what I understand, there's a fundamental problem:
There is no formal description of WikiSyntax. Its specification is:
"what the MediaWiki parser does".
It seems that it's not very hard to write a WYSIWYG that covers 99% of
all WikiSyntax, the problem is the remaining 1%.
That being said, I think WMF should try to tackle this difficult
problems. It's a huge job, but worth the effort.
-- Tobias