Acceptable translation : "You are the oldest out of us." ??? Duolingo counted this wrong, however the exact same sentence structure was on a different sentence and they did count the other one correct. Pretty sure "el" can mean "of" as well as "out of".
That translation seemed the most natural to me too; so I used it and it was accepted just now.
I prefer it saying: "Vi estas la plej maljuna el ni", it just feels more natural from an English stance. But would it still be grammatically correct, or are both ways appropriate?
The pair of sentences in the OP are not good. I wonder if this is an "acceptable" translation - because it's certainly not the "best translation." There's not a big difference between most old and least young, but there is a difference, and it should have been preserved in the translation.
I almost completely agree with you. Just consider a group of toddlers in a kindergarten, do you think it is proper to call any of them old, even though there sure is one who is the least young?
Yeah, I'd talk about the oldest kid in a kindergarten without a second thought.
...so we will eat you first!