I am using Traditional Chinese version of Windows 10. Today I installed Cubase 9.5.20 on it and found that it uses the default Japanese Windows system font (on Windows 10 till RS4 it is “Yu Gothic UI”, on RS5 or RS6 it is likely to be a new font family which is too confidential to say here) as the default font. It is appropriate to use the default Simplified Chinese font family for the Simplified Chinese UI of Cubase.
P.S.: I am afraid that it may be necessary to bypass the hinting data of all fonts used. DirectWrite in Windows 10 since RS3 could render fonts in good quality without ClearType Hinting.