I have been working on this a lot lately, we even opened a Premier Case about this, but there is no resolution. Also treat this as a feedback, because in Windows 10 there is something badly wrong when user wishes to change language interface (language pack). It mess up regional settings.
So, if we deploy a Win10 Enteprise computer with Finnish Language Pack, and user changes the language back to english, his regional settings will switch to en-us as well and we don´t want that.
So this default Match Windpws display language is something we need to get rid off.
Also, if comparing Language Pack management between Windows 7 and Windows 7, in seven it was lot easier from an end user perspective.