You're right, there are probably lots of sites misconfigured to not respect language headers, but we don't notice because English is the default.

However, the right solution is still to use the language header. I send that to them, they should use it to give me the right one by default.

One of the funny things is that this whole site is in an iframe; which breaks both Google Translate, and the Firefox translate feature. If you check, the outer iframe seems to indicate `lang="en'` and loads the iframe with `src="/coder/index.html?lang=en"`, but the inner iframe still gets a `lang="zh-CN'` by default until you use the toggle.

If you go to the eventual redirect source of the page with `lang=en` parameter, you get a `lang="en"` attribute, but it's still in Chinese until you toggle it with the menu: https://mimo.xiaomi.com/coder?lang=en

Anyhow, yeah, lots of pages are probably broken this way but we don't notice. But still, it has that info from your request, it should use it.