Source please? At a quick glance the film is co-produced by Taiwan, Hong Kong and China.

Yes it is, and US too. So the case is, Taiwan uses Traditional Chinese characters while China uses Simplified Chinese characters. But CT, HD is always treated as a Taiwanese film over a China film.

1. The director Ang Lee is originally from Taiwan, instead of Mainland China.
2. It represents Taiwan as the entry of Best Foreign Language film, instead of China.
3. On the posters, main typefaces, they are all in Traditional Chinese characters.

卧虎藏龍 is Traditional Chinese, 卧虎藏龙 is Simplified Chinese.

https://zh.wikipedia.org/wiki/%E8%87%A5%E8%99%8E%E8%97%8F%E9%BE%8D_(%E9%9B%BB%E5%BD%B1)

Thank you for your attention :) Please revise accordingly.