json text translate doesn't work with authors of unused paintings

That translation was deprecated in 24w33a, those paintings no longer have authors

You've misunderstood me, I think. I noticed the bug because I have my own authors for my versions, and those are the ones that matter to me, and which don't get translated. I was reporting using the default values so that you could see it wasn't an error of mine.

But fwiw, your current en_us.json (1.21.4-pre1), on line 5660 says:

painting.minecraft.wind.author": "Mojang",

So you do provide them. That's why I reported the bug using them.

If you're saying that the entire idea of an author for these four paintings was deprecated so no resource pack can ever assign an author to them, well, that's just weird, especially because I can assign a title to them.

I'm not sure if you'll see this because you resolved it, so if you don't seem to see it, I will file a new bug with a more precise description. It might be easier if you allowed a bug to be reopened once.

OMG, I figured it out – you didn't want authors for some of your painting images so you removed the ability for anyone to set authors for their own versions of those paintings.

"wither" is also non-author-able, and it's not an unused painting.

This is not a good choice. Mojang could have removed authors by removing them from en_us.json (and the other language files). Then they wouldn't be making a choice for everyone everywhere, just for Mojang. Instead, now it's just not possible for someone to create a version of Wither and get in-game credit.

Here, let me explain a bit more how it works.
The data pack defines painting variants: each painting file has a texture name, size, and optional title and authors. With a data pack, you are free to add new paintings, or modify any of those attributes for existing ones.
Now, since the vanilla paintings localize their titles and authors when present, a resource pack can modify those translations, but not create them out of thin air.
You're right, painting.minecraft.wind.author is still in en_us.json, but it's also in deprecrated.json, indicating its unused status.

Thanks for the added explanation, I really appreciate it! I just don't understand why Mojang didn't just remove authors from its files rather than, effectively, forbid everyone from ever having authors. Thanks if you have an answer for this.

Backwards compatibility and ease for crowdin source file updating. If the line is removed from en_us, and crowdin gets updated, it is removed from crowdin as well, removing the translations in older versions if you play them.