Same problem with kpdf 0.5.9 / poppler 0.6.4
in mixed pdfs. displays the english fine, but displays garbage for the chinese.
System is a clean install of Kubuntu 8.04
xpdf works fine.
kpdf 0.5.6 / poppler 0.5.4 on Kubuntu 7.04 worked fine.
Am filing here as I assume the problem is also poppl
I have to eat my words and withdraw the comment above.
After re-reading Pedro Villavicencio comments above,
I re-checked what was installed and compared the 7.04 and 8.04 systems,
and discovered poppler-data was not on the 8.04 system.
So I installed it, and as if by miracle, Chinese appeared.