In our Ultimate Font Guide we have written a short tutorial that describes what PUA encoded characters is and how to access these special characters/swashes in the fonts. The tutorial covers the usage of PUA encoded characters both on Mac and Windows.
Alternatively, you can upload your fonts to our free font management tool Fontcloud and view all characters in a single overview. The PUA encoded characters in Fontcloud are marked in blue, and are placed at the bottom of the font. Make sure that the toggle is set to highlight the PUA encoded characters.
If you have any more questions, feel free to reach out to us at firstname.lastname@example.org.