In the comment field on the waypoint dialog window, if you right click a word this is misspelled, you get a list of works for you to select the correct word. If the work is spelled correctly, you can lookup the deification.
I would think is part of the Mac OS and it would only take a click in XCode and mac users would have misspelled words underlined in red but Garmin is probable afraid Windows users would complain. Garmin should be used to complaints for all the grief Mac users gave in the past.