It's not site: that's messed up, it's the preferences.
For example, for one of my domains...
Search only for pages written in these language(s): English
Results 1 - 100 of 388 English
and the whole site is in English.
If you have it be set to...
Search for pages written in any language (Recommended).
Results 1 - 100 of about 208,000
This is why google.com shows tiny results on google.com and high results in datacenters! Because our search preferences are only set on a Google.com cookie. Google doesn't need to fix site: but needs to learn what English is.