The mod TrueType Font Replacement, aka BetterFonts is interacting strangely with the current 6.2.0-Snapshot version of MalisisCore.

The screenshot is of the Cubic Chunks custom terrain screen which needs MalisisCore to work. Only in the custom screens does the font (in this case Arial Black) not work. Cubic Chunks build is 775, TTFR is 1.9.1 and Forge is 2515.