Well research would have picked this up. Kobo Glo from what I understand, was never meant to be a quality PDF reader. Its able if it has to, but ePub is it's general format. That's where it's aimed at. It will even read Mobi, but again it's a bit hit-and-miss because as it will read Mobi, it is not specifically meant do so.
All this has been out there in the ereader community; no secret.
Portable Document Files are fixed to a size on their first build; and that's usually to the size and format convenient to the original author. Unless the PDF file was set-out for Kobe size and format then the magnify and pan is the best you can hope for. You could always redo the layout yourself if you wish. Plenty of programmes out there to do this.
Hope this helps