Out of curiosity, what happens when you go to this page in a private window:

https://productforums.google.com/forum/#!forum/en

Note the "en" in the URL and "English" in the language selector in the top right of the page.

The button text and input placeholder text is not in English for me, nor is the text at the bottom of the page. Blogger, Google groups and I think other Google stuff, like Flights, is the same.