These are the current recommendations to display Chinese characters on a browser and on the generated PDF.
Web browser:
Try several browsers and use the one(s) displaying the characters. I have tested Firefox on GNU/Linux and it does not display them, but Chrome does display work. In both cases, I wasn’t using the latest release, so the problem with Firefox may be solved.
PDF file:
Follow the steps mentioned in the solution for Japanese characters:
https://community2.invoiceplane.com/t/topic/6785/4
Caution:
The font(s) used for the Chinese characters will be not embedded in the PDF file, and to render the characters the font(s) must be installed in the local computer. If you want to embed the font(s), read this post: