Steps to reproduce:
- Set Text Viewer font to Consolas
- Preview the following text:
English text
Chinese text 中文
English text
1 Like
After unchecking, the "中文" is wrongly displayed to other chars. And the font is still inconsistent.
Looks okay here with the English version of Opus (12.33):
If you look closely, you can see that the font of "English text" at the top is obviously wider.
To make the difference more obvious, you can change the font to Consolas or other sans-serif font.
At least the characters seem to be correct 
Looks like Opus 13 has this covered:
Pasting as ANSI format causes this.
It would be nice if the plugin could automatically parse the format, just like Notepad.
You can try to restart DOpus or reopen the viewer panel. The bug will appear.
This is something the Windows rich text control does. If there's a character that cannot be represented by the font you have chosen for it, it'll change to another font that can represent it. When that happens again for the original language, or may not choose the original font.
We don't really have any control over it (other than the possibility of re-writing the viewer with a completely different control, which may happen one day but not in the near future). It's down to the OS and fonts.