Customers are often satisfied about the PDF generation within Mendix. For now, most of the configuration I had to to were custom Fonts.
However, there are options to set the Author, etc. in the metadata of the PDF as well via the fop.xconf-file. Source: https://xmlgraphics.apache.org/fop/2.7/metadata.html
Either it be configured via static values in the fop-file itself, or even dynamically at the point of PDF generation in the specific Mendix application.
I asked the question to Mendix Support and they gave me this answer:
Mendix 9.10.1 PDF generator allows to fill in properties as 'Title', 'Author', 'Subject' and 'Key words' (I can find the 'Title', the other properties I can not)
It seems there is no way to do that