We try not to accept literal answers if they sound too bad in English. A lot of people try to learn both languages by using this app, and allowing incorrect English also annoys many users who are native speakers of English. (all accepted answers can get shown to users even if they don't input them).
I too put "Who has told it?". I get your point, though; that's not something I'd actually ever say. It then becomes an exercise in remembering what DL will and will not accept. All that being said ... the worst still is the accepted translations for "På lördag är helg". :-)
We could accept a lot more strange answers if it weren't for the fact that any sentence we enter as accepted will also be shown to users as "another correct answer". Duo might change that, but if they do, we'll end up with another set of difficult decisions, so I'm not at all sure it will help that much even if they do. But in that sense you're right of course, if we could just accept all answers that are close, it would be less of a guessing game, because so many more answers would be accepted.
Anyway I think what is most important is that the best and most natural translation should always be accepted, so we're always especially grateful for corrections concerning those. And you're right it's super hard not only to find the best translation, but also to draw those lines – what is too bad English or too far in meaning?
Yes, that's basically what I was saying. The balancing act between literal translation and English that would actually be used isn't always consistent, so there are certain sentences where I have to remember what DL is looking for. I think it would be really hard to find the perfect solution, so it's not a complaint. I think you all do a fabulous job. And thanks on the "det helg" correction, too - I couldn't remember if I needed it or not.
I ran across "Bordet har alltid stått vid fönstret" which I think is a good example of the difficulty in finding the right balance. The recommended answer was "The table has always been by the window", which is probably the most natural statement in English, but the more literal "The table has always stood by the window" would be perfectly fine, too. You moderators have a hard job! Tack så mycket!