2, When I run "make en" or manually compile ma-cb-en, I got an error that \secretsetup is undefined. I think my ConTeXt is new enough: ConTeXt ver: 2007.04.17 12:51 MKII fmt: 2007.4.20 int: english/english
It has nothing to do with your system's ConTeXt; it's defined in t-setup.tex in the contextman directory, but it can't be found because the compilation takes place in some subdirectory (like en/). You can work around it but setting TEXINPUTS to the appropriate location (with a trailing colon! Don't forget the colon.), although I'm not sure how it works under Windows. It should probably be set in the Makefile anyway.
3, I've never used svn before, so I'm afraid if I upload my source to the svn server, would it harm other files? I only made change to makefile and create a folder called cn (for Chinese).
I think it shouldn't, but I leave the details of the commit for others to explain. Please do it first so that I can make the necessary changes for French ;-) In any case, please please please consider using the letters “zh” which is the code for the Chinese language, and not for the country, China. It's bad enough that ConTeXt tags British English with the international code for Ukrainian ... ;-) 祝你翻译成功！ 此致 敬礼 周恩德