1. Create a SINV

2. Add a stock, input the description in Chinese characters

3. Save and preview the transaction

4. Notice that the description is still exists

5. Export to PDF

6. Open the exported PDF, the description is missing

7.According to DevExpress, the reason is that the Font used doesn’t support foreign characters

https://supportcenter.devexpress.com/ticket/details/t674068/support-chinese-characters-in-xtrareports-export-to-pdf-functionality

8. In order to show foreign characters, 'Arial Unicode MS' font needs to be installed

9. After that, change the font to 'Arial Unicode MS'

10.The characters should be showing here

Please refer full documentation here. 

Thanks :)