I am suffering from the same situation: Garbage/No Fonts on OSX with Forge 1.7.10 on splash (and subsequent) screen. No issue when running standard 1.7.10 or latest standard version (1.8.7).
My config: IMac 27", 16GB, i7, 3,5Ghz, Nvidia Geforce GTX775M. I tried the recommended (1481) and the latest version (1448) of Forge for 1.7.10. Both have same outcome. Since I am planning to run Flan´s Mod, I am dependent on 1.7.10.
More Details:
Bootstrap (v5)
System.getProperty('os.name') == 'Mac OS X'
System.getProperty('os.version') == '10.9.5'
System.getProperty('os.arch') == 'x86_64'
System.getProperty('java.version') == '1.6.0_65'
System.getProperty('java.vendor') == 'Apple Inc.'
System.getProperty('sun.arch.data.model') == '64'
Is there any recommended work around here ? Any help is highly appreciated!