My guess was correct after I did an experiment in SSH. Chinese font is missing in the build.
1. Install a Chinese font.
pacman -S opendesktop-fonts
2. Flush font cache. (I don't know if it is necessary. I just did.)
fc-cache -vfs
3. Reboot Runeaudio
reboot
4. Enjoy.

- IMG_2483_1.jpg (82.84 KiB) Viewed 8635 times
I'll try other fonts to see if it is possible to make it look nicer, when I have time.