My Chinese collaborator has been using the betas for the last two years, and when I open projects that she has set up, certain interface features, like these, are in Chinese:
[attachment=0]Screenshot 2020-11-04 at 21.14.43.png[/attachment]
So I presume most of her interface is in Chinese. That said, I’m not sure that either all the interface has been localised in Chinese—there have been instances of English terms within European language interfaces—nor can I attest to the quality of the Chinese … one of my Mac using Chinese friends has told me that there are some wrong translations in that.
You could try downloading and installing the beta to see for yourself. Just (a) make sure you install it in a different directory to your current version, and (b) if you open any of your current projects in the Beta, it will make a backup copy in the old format, but any work you do or changes you make to the v. 3 project will not propagate back to the version 1.9 backup copy.