I think I spent about 20 hours testing all possible combinations of mods and solutions and finally, I got my Chinese sign blocks.

Mac also has its own quirky way of dealing with Java and Chinese (for example, I have to switch the Chinese input method on before I start minecraft or it won’t allow me to type chinese)

All you need to:

1. make add NihongoMOD_v1.2.2_forMC1.5.1.zip into client-side mods.
2. modify client jar: minecraftedu.jar (change jh.class)
3. add a new font.txt (utf-8, long Chinese version) to server jar: minecraftedu_server.jar