On El Capitan and before I could set a different format language than the display language in OS X. So the UI of OS X would be English, while the date and number formatting would be Dutch. However this setting was changed when upgrading to macOS Sierra, it now uses English for both display and formatting. I would really love to revert this change to what it was on OS X El Capitan.
OS X El Capitan:
Best Answer
It appears this can be done from the command line. For example Dutch format language (the
nl
part) with Netherlands (theNL
part) set as the Region, even with English as the UI language, should result when you execute this in Terminal:This was found at tidbits.com.