Comment 12 for bug 1850275

There is no en_NL locale in glibc. I believe you are talking about a different project, maybe about some non-upstream patches for glibc. Of course, localedef tool exists in order to allow the users build and use their own locales, even without the root permissions. So you may have and use whatever locale you want. However, I'm trying here to avoid inflation of locales. The problem is that each new locale, even if it source code is short and easy to implement, makes about 2 MB binaries. This multiplied by about 200 or 300 locales we currently provide may make a problem. Distros are already complaining about it because the locale binaries take too much space both in installation media and in the users' computers.

Of course, en_EU will not work for everyone. Even if it works for 8 or 12 countries I'd be satisfied.