so, there are steps to translate:
Create two filse in loc folder:
where xx is first two letters of ISO 639 language code
xx.labels.lng - all labels to translate in utf8 (without BOM). Format is: labelnumber=labeltext per one line. No CR or LF charactes allowed inside labeltext. One line of file - one label.
xx.lng.lng - names of languages in xx language
It should work, but only in case current font file support new language. Currently isotoxin uses OpenSans font. It located in themes\def
folder. Considering the size of font file, I think it doesn't support chinese glyphs and You should use another font. Create new theme like dejavu (same as def, but uses dejavu font. All other features of def theme are inherited) and setup another font. You can use system fonts. In this case just edit struct.decl
and write names of system ttf files, no need to copy them into theme folder.