Hello Nickel,
having proper Chinese font in PDF is a tricky issue.
Yes, having a device type assigned to your printer output device which supports chinese fonts and charset helps. So SWINCF is fine.
But you should also ALWAYS select a Chinese font in your form/style, such as CNHEI or CNKAI if you want to print Chinese chars.
SWINCF does still print your Chinese text even if the SAP font is HELVE or COURIER, but the actual PDF font and encoding data may indicate a "wrong" Western font (such as Helvetica, Times-Roman or Courier) which will not display any CHinese on any PDF viewer.
BTW; if you open your PDF with notepad, you can see what the current SAP font and device type is in some comment lines starting with %
Best regards,
Alex