Why changing the default font? That could result in more changes than you want to. You can create any number of your own Font names.

NimbusLookAndFeel nimbus = new NimbusLookAndFeel();
     UIManager.setLookAndFeel(nimbus);
     nimbus.getDefaults().put("internationalFont",
           new Font(Font.SANS_SERIF, Font.PLAIN, 22));

Here I just chose the name "internationalFont". You can make up your own names.