Thanks! There is a corollary to this that would have prevented all this - when I went back in the Chrome settings and set the settings to the same order, it reset my header to this: "en-US,en;q=0.8,ko;q=0.6" - which makes things work for all sites again. I haven't touched my language settings since ~2012, so it's possible Chrome "fixed" this a while back, but didn't change my existing settings.

Please don't do this... I detest sites that try to be clever and serve me Simplified Chinese even though I only have zh-hk in Accept-Language:.

I already have exceptions for things like that. I think our code handles zh_{CN,TW,HK} separately, as well as things like pt_BR vs. pt.

    > curl -I -H 'Accept-Language: zh-hk,en;q=0.8' https://dolphin-emu.org/
    HTTP/1.1 200 OK  # No zh_HK translation (yet!)

    > curl -I -H 'Accept-Language: zh-cn,en;q=0.8' https://dolphin-emu.org/
    HTTP/1.1 302 FOUND
    Location: http://cn.dolphin-emu.org/?cr=cn

    > curl -I -H 'Accept-Language: pt,en;q=0.8' https://dolphin-emu.org/
    HTTP/1.1 200 OK  # No pt translation (yet!)

    > curl -I -H 'Accept-Language: pt-br,en;q=0.8' https://dolphin-emu.org/
    HTTP/1.1 302 FOUND
    Location: http://br.dolphin-emu.org/?cr=br

i18n is hard but I think I've been doing a fairly good job on it. Proud to have more than 50% of our visitors from outside of the US!

Having now read the full code and not just the diff, I have to say it looks pretty good. I note that plain "zh" is not redirected to the cn site. ;) Whether it should or not is debatable though -- I actually think ignoring "zh" altogether is a rather prudent move if it is intentional.