Translation:Didn't you already go to seventh grade last year?
"Didn't you go to seventh grade already last year?" was marked wrong. I would argue that the place of "already" isn't that rigidly fixed in English, but a prescriptive grammarian may know better.
I'm by no means a grammarian, but I'd say that the "already go..." version sounds more natural and is probably used more often. But I'm pretty sure your version is used, too. Unless it's clearly grammatically incorrect -- which I don't know -- it seems like a good alternative translation. You might Report it, if you already didn't do so / didn't do so already. :-)