Hi Adrian;
Got it ....
1) Use PDF ToolKit (free edition) - my favourite PDF tool I use called from PB Apps. ;-)
https://www.pdflabs.com/tools/pdftk-the-pdf-toolkit
2) Use the command ... for example
pdftk MyDW_PDF.pdf dump_data output info.txt
3) Edit the TXT file and replace meta data values as required
Use FileReadEX, FileWriteEx to automate the TXT file values via PowerScript
4) Run the PDF Toolkit command ...
pdftk MyDW_PDF.pdf update_info info.txt output MyDW_PDF.pdf
5) New PDF file signature ... (from my quick test a few minutes ago)
/Creator (PScript5.dll Version 5.2.2)
/Title (PDF Wars)
/Producer (Lucas films)
/Author (DarthVader)
/ModDate (D:20191114105002-05'00')
/CreationDate (D:20191114105002-05'00')
HTH
Regards ... Chris