The link you provided is already the official documentation. So, there's nothing more official and comprehensive as-of today.
So I guess the answer to your question is two-fold:
- either file an enhancement request in the Hibernate issue tracker (better with a proposal)
- or read the corresponding code
I know this isn't the perfect answer you dreamt about, but this is actually all you have today.
But the good news is that the project is open-source, so you have all you need to help improve it :-).