Set different display and format language on macOS Sierra 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:



macOS Sierra:
It appears this can be done from the command line.  For example Dutch format language (the nl part) with Netherlands (the NL part) set as the Region, even with English as the UI language, should result when you execute this in Terminal:

defaults write NSGlobalDomain AppleLocale -string nl_NL


This was found at tidbits.com.