Is "what all are these" even correct English? "What are all these" seems more natural to me, but unclear if the meaning changes.
Here are a few results from a quick search:
Through Google it is possible to see some of the book "Talking Appalachian: Voice, Identity, and Community" which on page 45 mentions this "Addition of all after pronouns to indicate inclusion." Regretfully I can't copy and paste even for purposes covered by fair use (and similar laws). Here's a books search for the title:
Not definitive but:
[Question] Which is more grammatically correct: "what are all the…" or "what all are the…"?
[Answer] Colloquially, I've heard the second option throughout my life, as part of the regional dialect of the Appalachian Mountains in NC and TN, even though most of us know it is grammatically wrong.
Another discussion of it, with a couple of comments regarding it as slang: https://www.englishforums.com/English/IsWhoAllAndWhatAllProper/pmrjl/post.htm
How widely it is used I don't know. I am with you in considering "What are all these" more natural for myself.
Interesting! So if "what all" is technically incorrect, "what are all these ones" should be at least be accepted by Duolingo, yes? It seems that is not the case at the moment. Thanks for the thorough answer.
From Merriam Webster: "the book was about family, social differences, and I don't know what all else", and "What made you want to look up what all?" Are examples of use.
From what I see in those examples, What all is working more like a plural what, similar to the use of you all to make a plural you. And so, it's different from using the sentence "What are all these", since that form is using the all to modify these, not what.
So, if you want to translate it without using what all, use a single what and it would be more exact.
I think we need to look at "what all" as being in the same ilk as "you all" being the plural of "you" (eg iksā vs iksāt). It's just the plural version of "what" really. Maybe I'm not as smart as everyone else on here, but that makes perfect sense to me.