http://forum.unity3d.com/threads/text-characters-not-visible-in-the-built-game-app.225594/
http://docs.unity3d.com/Manual/class-Font.html
so from what I'm reading, if a Font family doesn't contain a certain character, Unity tries to pull the character from a fallback font. You can specify the fallback font, and include it in your project even. But does it warn you if a character isn't found in either, and is then using an OS-installed font? Of course not! And so it silently fails on other OSes that don't have whatever it's trying to find