I've reached a point where the Mac almost produces the same output. But there is a residual nagging font issue that I can't figure out. Please see my attached screenshots below.
The first image shows the output from my Linux box. All fonts are correct.
The second image shows the output from my Macbook. Only the top-level topic font is correct. The others show a Serif font that's not correct.
The third image shows how the hierarchy looks like in the DITA Maps Manager.
I put all customizations into a "Customizations" folder that I created. I copied the Customizations folder from my Linux box to my Mac. I have checked all the files within Customizations, but cannot see where the font discrepancy comes from. I've checked my "font-mappings.xml" file, as well as others. Perhaps I'm looking in the wrong place?