Norden is inconsistently translated in a couple of places. In a previous question, it was translated as "the North", and I've just been marked wrong for translating to "Sweden is in the Nordic countries" even though "Nordic countries" is the accepted translation elsewhere.
Like several others here, I got the error, "You used the wrong word," from Duolingo for the English translation "Sweden is in the Nordic countries." This, even though "the Nordic countries" is one of the translations listed in the mouse-over tooltips! I still don't see an explanation why this is incorrect. For a native English speaker, saying that "Sweden is in the North" is a bit ambiguous, and not something we'd likely say (IMO).
OK, this is how I feel about this right now. You might disagree with me right now, and I might disagree with me later.
"Norden" sv is Denmark, Finland, Iceland, Norway, Sweden. https://sv.wikipedia.org/wiki/Norden
There is no English speaking region where "the North" automatically means those countries. (It might need to be "The North" if it were correct.)
in virtually all English speaking regions the countries in "Norden" correspond to "Nordic Countries"
there may be many accepted en. answers that include "Nordic" but the main en. translation "Sweden is in the North." is very very bad at the least, or just wrong.