In fact, the path does not contain unicode characters (although some of the .html files are encoded in UTF-8), all filenames and file paths are typical A-Z letters. In any case, I'm having no problems on other language versions of Windows, including Spanish and German.
In a screenshot provided by the client, setup factory is correctly using the hard paths for the directories, rather than the corresponding names in Chinese. (C:\Documents and Settings\Users\ApplicationData\...\)
Any other ideas? Can I rebuild in some more favorable way? Or potentially have the setup suppress the error and complete installation, while generating a log of files not installed?