It would make sense if websites had a standardized response with the language preferences of _their content_, and browsers simply responded with whatever their

It would make sense if websites had a standardized response with the language preferences of _their content_, and browsers simply responded with whatever their user chooses among the available ones. Something like { 0: de, 1: [en,fr], 2: [ru,es], 999: [zh,jp,...] } where the keys are an arbitrary 'priority' score chosen by the server. 0 would be the original language, then in this example maybe 1 could be full human translation, 2 partial human translation, 999 machine translation. The browser could keep its language preferences client-side and simply request their favourite language among the available ones.