I noticed that if you select "default" under Custom Language Fonts for both Japanese or English (United States) you cannot hit the OK or Cancel buttons.
However, when I tried German (Germany), selecting "default" was possible. This behavior seems odd to me, can everyone select "default" for their languages?
Also, on my PC, even if you change the language, the settings always changes back to "Afar (Dijibouti)", I was wondering if this is normal behavior.