All of the updates to the BIZ products today state “Improved : Refer to official documentation for the list of new features and improvements”. Where is this “official documentation”? There’s no information in any of the online help files/manuals. We have all these updates and no idea what was updated.
In addition, there’s a message that older versions of Delphi will no longer be supported, with a link to a BLOG post - but the link is dead.
Hm, the "official documentation" is the online help files/manuals. 
For example, here are release notes for Sphinx, which received the major of new features of this BIZ release:
The blog post is published now.
I’d gone to the Aurelius, XData and Sparkle guides and none of those have release notes. I did see notes in the documentation after installation, but I prefer to see what’s new first, to see if I want to risk an upgrade.
I see the blog post is up now. Thanks.
They all have, for example Aurelius: What's New in TMS Aurelius | TMS Aurelius documentation
As said, all release notes for all products are available online in their documentation.
Nevertheless, we have updated the version history notes as well, in the web site.