So this is why installing a second language worked fine before, but now it fails.

Before, when the second language I'm trying to install (English (US)) was a regular language pack it all worked fine, but now when I try to install it on a new computer it tries to install the English (US) Local Experience Pack instead and fails.

One would the think that English is a rather well known language that doesn't need a Local Experience Pack to improve translations (from English to English?) but apparently not.