I wrote before Christmas that I was making the font validator run standalone as mac os X command line binary, no need to install mono separately. So it comes.
There is a FontVal-MacOSX-*.tgz under
(current 2016-01-06):http://sourceforge.net/projects/hp-pxl-jetready/files/Microsoft Font Validator/
If you have an up to date freetype (from macport/homebrew, Xquartz[?], or built your own), you just run it plain. If you have a vanilla mac os X box without any of those, you set DYLD_LIBRARY_PATH to where you unpack the "Darwin" subdirectory - there are just 3 files, the binary, and a subdirectory of up to date freetype dylib, and libpng (which freetype depends on), which you don't have to use.
It is mainly tested on Mavericks, so I'd like to hear from people trying on Yosemite and El Capitan.
I am having problems making the GUI run standalone on Mac os X without mono. More details about this later.
Please feel free to click http://sourceforge.net/p/hp-pxl-jetready/donate/