Not too much discussion on this topic...my wife has the Blackberry Curve 8330 (which is now deemed "old").
She would like to switch to a Traditional Mandarin Chinese OS....there was one thread about Simplified Mandarin on the 9700, but not sure if that applies.
You want traditional Chinese characters? I know you can get the simplified set, but I think the traditional character set is a different OS. You should go to your carrier's website and see if they have the OS available for download there.
Failing that you'll need to get an OS from a different carrier that supports it.