Updates are still unavailable.
What I had thought was a working system turned out that it wasn’t working that well. It worked when I ran updates and it worked for others on the test site. But in production, it worked only for a few. Some updates were given in zh-*. So instead of keeping it up and giving people bad updates, I’ve opted to switch off the updates altogether until I can get my stuff together.
So… back to the drawing board (but not square one).
My apologies for those affected by the locale switch. But I thank you all for the precious feedback.