/Set-SKUIntlDefaults: Sets the default system UI language, the language for non-Unicode programs, the "standards and formats" ...

/Set-SKUIntlDefaults:
 
  Sets the default system UI language, the language for non-Unicode programs,
  the "standards and formats" language and the input locales, keyboard 
  layouts and time zone values in a mounted offline image to the
  Windows default value specified by .
  This command is not supported against an online image.

    Example:
      DISM.exe /Image:C:\test\offline /Set-SKUIntlDefaults:en-US