Yeah, I'm the lead on a bunch of websites that all have to be localised.

There's a lot of weird footguns to watch out for, and a lot of retraining devs when they're used to only working on a single language/locale.

Two biggest head scratchers I've had to deal with are computers treating "fr-FR" different from "fr-fr" (due to file system case-sensitivity differences between developers), and having to undo the coded assumption that languages and locales follow an [a-z]{2}-[a-z]{2} pattern (e.g. "en-gb") once we stumbled upon Latino Americano: "es-419".

EDIT: My left ear really loves the Erlang talk.

This fixes it:

const audioContext = new AudioContext();
const audioElement = audioContext.createMediaElementSource(document.querySelector("video"));
audioContext.destination.channelCount = 1;
audioElement.connect(audioContext.destination);