The win32 release of TeXstudio is distributed with elder freetype.
It lakes of Adobe's CFF support.
While using buildin Chinese font "標楷體", the buildin pdf viewer renders it incorrectly.

As I replacing the buildin freetype6.dll with newer release, it renders correctly.

Please provide a minimal .tex file so that we can test this.
Use Windows built in font "標楷體", and Compile with xelatex.
The example does not work for me.
Is this font only available on chinese systems?
How about
I chang its name to English one.
This only works on Windows.
If it still doesn't work.
Try this repo: https://github.com/wengan-li/ncku-thesis-template-latex.git
It packs 標楷體 for non-Windows user.
Because of historical reason, 標楷體 is a composing font.
Composing font is heavily depend on Adobe's proprietary technology.
The image is form http://www.dynacw.com.tw/business/embedded_digitype.aspx
fixed.
You can get the latest development binaries here:
https://sourceforge.net/projects/texstudio/files/texstudio/TeXstudio%20development/