@Caty, All the maps are working properly now. I found out that only one mapset (Topo South China) didn't work because it was ''locked''. After I run the notorious gimgunlock.exe, bang, all is well!

@Gieman, @aekhong, I have gotten proper Chinese.gtt and corresponding *.bin files. Now my Montana 600 is able to switch the UI to CHN and of course, the latest 'genuine' shift-corrected CHN mapset has got proper CHN font display. Cheers, everyone for your input.