How is the language linked to the locale ?

We have a client using Enterprise Management with operations across the English speaking world (USA, UK, Australia, South Africa). In order to avoid having to manage translations, they would like to use ENG as a common language across all locales, but of course the date format is different in the US (mm/dd/yyy) as opposed to the others which us dd/mm/yyyy.

In an ideal world each user would select their own locale (en-GB for UK, en-US for USA, etc.) and those locales would all display the screens and data using ENG but with the correct date format for the locale. For the UK however the screens and data are displayed using BRI when selecting en-GB. How do I configure Enterprise Management so that the front end UK locale (en-GB) uses the back end ENG language ?

Thanks in advance.