Version: Magento 2 CE 2.0.6
language package: https://github.com/Magento2Translations/language_zh_cn
I have installed the language package. And it shows in the console. But I the front end and admin console still in English.
Does anyone know why? Thanks in advance!
Finally I can provide a solution
1. https://github.com/splendidinternet/Magento2_German_LocalePack_de_DE shows 1. a manual install and 2. a composer based install of the language pack. For convenience I used the composer based install, but it did not work for me. Though, the manual install worked.
2. "[*] Use Website" does NOT refer to a visitor's web browser (which provides a preferred language, e.g. en_US, to the Magento website). It referres to the 'Website' in the Magento's "Website - Store - Store View" terminology / hierarchy. Settings in the top of the hierarchy are inherited down the path to every store view. With "[*] Use Website" we practically use the settings which are defined 1 level higher. To override such a setting in a store view, you have to uncheck the box.
3. Here is a great page with images that shows how to enable (a previously installed) language pack in Magento. For the store view, as well as for the admin area. It's for a french language pack, but of course the shown Magento settings work for any language pack you might have. If you are new to Mento you will like it:
http://imaginaerum.github.io/magento2-language-fr-fr/en.html