Oookay, so ran into an rather unusual find regarding PDFs. When an accessible PDF is opened in Reader, viewing the Document Properties > Advanced, the language that was set (English), is not being displayed. However when you go to Edit > Preferences > Language > Application Language is showing indeed that English was set. Of course viewing the PDF in Pro/DC, the Language setting shows up in the Document properties.
Anyone have an idea why this occurs or a workaround to force Reader to display it in Document Properties? I have replicated this across several PDFs from several sites (that had tagged and accessible PDFs) and cannot seem to figure out the how or why.
Any insight would be appreciated!
Adobe Reader is a viewer not a processor PDF application.
So, Reader has no access to a PDF's Document Properties "Advanced" tab informtion.
(Language of the PDF content is one of these.).
Note that a PDF document's Language is a requirement for an accessible PDF (which is to say / mean the PDF is ISO 14289, PDF/UA compliant as this is what defines/establish a valid accessible PDF).
The PDF document content Language Is Not the same thing as the software application "language". The software application 'language' localizes the software for the country/region you are in (Middle East, Germany, China, whereever).
Using appropriate tools (such as those available in Acrobat Pro) you can view the PDF doce ument's Structure / Tag Tree. within that you can access/view the document's language and any inline language designations other than that of the document content as a whole.