Thank you. this was a simple example of literally translating word for word. I believe that a truthful translation should be an accurate presentation (albeit in another language) of the intent of the original. I don't think the words need to correspond closely.
Of course the results would depend on the perception, attitude and general mindset of the translator. The idea of testing a translation by doing a reverse translation should reveal deviation from original intent, but where the intent is preserved but the words differ, (as in your example) then for me that works...
What you write is generally accepted as true for translation nowadays. But please consider that this is a basic course for beginners, many of whom do not even have the benefit of speaking native English. So the ideal of a close translation frequently runs counter to the purpose of teaching.
This is particularly true on Duolingo because the default translation into English is automatically chosen for the "translate into Swedish" exercises. Hence, if we want to teach a Swedish concept, we may often have to choose unidiomatic English as the default, because you will otherwise never be asked to translate into that construction in Swedish - however important or idiomatic it is.
So the reverse translation test is very relevant to the course, whether also to practical scenarios or not.