I'm not sure about that workflow specifically, but sounds like ccc has the right of it. I've not used it. You might try out one of the other markdown to PDF workflows in the Workflow Directory. Unless there is some specific function if this workflow you need (for instance, getting it into a specific app like Documents that can do that). There is at least one that converts markdown to PDF directly in Editorial using Python, and saves it in the app's Dropbox folder, where you might then preview it right in Editorial and open in other apps as needed.
This one by Mason Phillips generates a nice PDF from markdown. I had to make a tiny edit to the code for printing (not to print, but for alignment on the page), but it might not even be an issue, since the resulting PDF looks great! I need to fiddle, but that issue may have been my own. If you get the same problem, if you print, I'd be relieved to know/share my fix, whether it's the proper way or not. Cheers.