Adobe now makes the straightforward claim that it supports PDF/UA:
Where is this new feature enabled?
Using Acrobat Pro XI - provided that I am also allowed to use PAC2 - I am able to achieve PDF/UA compliant documents to the best of my knowledge. Some steps are tricky and/or inconvenient, but it can be done. I have been experimenting and collecting tips and tricks on this ever since PAC2 was first published. Very recently, in a burst of enthusiasm over the great news that the impending 508 Refresh will embrace PDF/UA, I consolidated all the tips and tricks and posted them at TaggedPDF.com.
I am not sure if this means that Acrobat supports PDF/UA. Certainly there is much that Adobe can do better. I have posted my suggestions in the Acrobat Feature Request forum here, but to no avail at least to date.
In spite of my best intentions I have not made time to put my trial install of Acrobat DC through its paces, and since I only have four trial days left I may have missed the opportunity. In my limited experience with DC it seemed to have very similar accessibility remediation capability to Acrobat Pro XI.
I post as Kenny Moore in your excellent PDF/UA LinkedIn forum, by the way. Good to see you over here.
a 'C' student