- I'd use a link to the official documentation for the list of supported culture codes: http://wix.sourceforge.net/manual-wix3/WixUI_localization.htm
- Giving multiple values for -cultures does not produce multiple installers. Instead it provides fallbacks (search priority is left to right) for a single installer.
- -cultures can also handle semicolon separated lists (which nicely matches CMake list convention) which may be a fact that should be documented as well