The PDF metadata has its own series of tags that are different form photographs, MS Office files and other files. There is a separate "PF" tab when viewing the file properties for one file in Windows Explorer.
And from what has been shown, you have not even seen the metadata stored as XML data and that includes the electronic copyright some descriptive fields and a lot of other standards all listed under the "Additional Metadata" button.
You can use JavaScript to create custom tags and values and since all the PDFs in a folder should have most of the same tags and data you could create an action to add this data with Acrobat Professional. You also might want to look at Debenu PDF Tools Pro 3
If you want to view this added data you will need to find someone to create a custom version of Windows Explorer file manger.