Installing and Setting New Site/Blog Languages post WP 4.1

Hi,

I’m running 4.4.2 and running a multi-site. As of 4.1, the languages are now selected in Settings -> General.

The problem I’m having is that I’m trying to set two sites to German and Dutch but the only options in the Settings are “en_US”, English (United States)” and Chinese.

I’m only trying to set the site language. The admin area needs to remain in English. How are new languages installed since there is apparently no need for MO / PO files?