> In your browser's settings you can configure a list of languages (country-specific if desired) which get send with every request.
Customising this list at all makes your browser fingerprint thousands of times less common than it was before you did this, and many websites you visit could then probably uniquely identify you as the same user across all of your sessions.
That and a thousand other things. A highly privacy focussed browser could offer to enable this setting only on whitelisted websites (and send 'en' plus a bunch of random language codes on others).
Not if the random part of the list changes with each request.
There are two ways to defeat fingerprinting: 1) make everyone look exactly the same (pretty difficult to do), or 2) introduce enough noise and randomness to fingerprinting signals to each request so that each person looks like many different people (much easier to do).
