It looks all fine. I don't have a 500 to compare with, but my 201, 99 and Bernina 730 have the most even neat stitching of of the vintage machines I have used. I assume his has mostly to do with machtching correct needle and thread for the fabric, regular the adjustments, (things like that). Getting a perfect even stitch can some times be a bit of a trial and error thing, I once went from a rather fancy machine to a 99, and it did the job with ease (same needle and thread). Some models are just easy to sort out. For the zigzaggers, a neat zigzag or satin stitch is a good test to compare with.
It's not always easy to know why it doesn't turn out to give a so called perfect stitch, but I guess most models should be up to it. A 99 is the most basic machine, even though the bobbin case and oscillating hook was top of the line at one point, a 500 should be a step further. The bobbin is placed in front of the needle and feed dogs, not to the side of it?
I'm just thinking out loud really, I'm sitting here testing my buttonholer and wishing I had a large spool of blue Gütermann thread.