[zarzavat]

I can say that it doesn't work on Google Docs, which uses the IP address's language^, even though my language is set to en-UK. Unless you're logged in, but I often have to use incognito because of another misfeature which is that Google will dox you to other editors if you access a public Google doc while logged in. Googlers reading this comment: please fix this!

^ I wonder how this works in places like Switzerland and Belgium that have more than one language. The notion that IP addresses can be mapped to languages needs to die.