Please accept that you cannot use xml tags that contain Chinese characters. It does not matter whether you convert the wxStrings or not, it is illegal.
If you write something like
key << _("/file_groups/group") << wxString::Format(_T("%d"), i) << _T("/") << _T("name");i.e. you translate the path, then this does not only make it impossible for people who are unable to speak Chinese to find an error in such a file, but it is also illegal.
It might even appear to work out of pure coincidence, but at some random point, it will fail, and we will not know why!
Please don't do such things, you're opening Pandora's box. Configuration keys should not be translated, and they should not contain special characters.
Storing non-ANSI characters as data is a completely different thing, this works fine since end of December, and you can certainly do it.