When a user adds asian characters to his moodle instance, seeing it in the website is not a problem however when trying to download a pdf file with those characters will either display no characters or question marks 
The underlying issue seems to be that there are no fallback font when the tcpdf method calls setFont method, as a font like stsongstdlight would work.

As stated in MDL-47948, this may be a limited audience issue, however in language courses it becomes unpractical.

To replicate issue:

• Create a course and name it with asian characters (ie: 中文鍵盤/中文键盘)
• Navigate to Site administration > Reports > Custom reports
• Click New report
• Name new report as you would lik
• Set report source as "Courses"
• Click save
• Click Preview
• Set Download table data as PDF and press Download

Given pdf will display question marks instead of desired characters