What is a .Spritefont file, and how do I create it?
There is no SpriteFont, you can import fonts directly.
Adding Special Characters to SpriteFont
You need to use the decimal value for your characters instead, check out this site which will show you all of the representations. (You can change the value in the URL to find different characters) Your correct XML should be: <CharacterRegions> <CharacterRegion> <Start>▲</Start> <End>◄</End> </CharacterRegion> <CharacterRegion> <Start> </Start> <End>~</End> </CharacterRegion> </CharacterRegions>...