I have about 30 PDFs on the KDX. All of them pick up the correct Titles and Author from the metadata. These are a mix of PDF ebooks that I have and technical documents that was converted from Word. I also use Adobe Prof. to edit the meta properties. These files was dropped onto the KDX (w/o going through any sw like Calibre).
I have one document that has nothing in the tag and the KDX uses the filename as the title. This one was password protected and I could not edit the metadata.
The other one was generated from Word->PDFs and also has no metadata.
I will look into this more and report back if I found anything.