I ran across this issue while working on multi-language custom certificates. The included font list was reduced in MDL-16802 to reduce the space used by lib/tcpdf/fonts folder for Moodle 2.0 release. However I noted during this project that CID0 (asian language / CJK fonts) are not embedded in the fonts folder. They are treated similarly to core PDF fonts in that they are only accessed by reference in the PDF files that use them. For practical purposes this means that their removal didn't save space (only the few characters for the definition file) and as a result its impossible to create asian character based PDF files without downloading and installing a custom fonts folder.

There may only be a limited audience for this issue, but I think it would make the Moodle core PDF library more asian language friendly.