Yes, you're right. And I have to say, a lot of the translations in the lesson material are pretty weak. I completely understand your frustration, but I don't know what to recommend other than pounding your fist on your desk and swearing a lot (Ty it! That's what I do!).
(U.S. speakers at least) often translate "man" as "you" meaning "anyone" or I guess more like "a nondescript person" as opposed to "you" a particular, specific person. This is really confusing in English because we have one word that does it all -- "you". In German, if they mean a particular, specific person they can go with "du" or "Sie" (or "Ihr" if they mean a specific group of people), and if they mean "a nondescript person, nobody in particular", they can go with "man".
In the real-world translations, I often translate "man" as "you" myself (because that's what I'd say if I were expressing the equivalent idea in American English). But this is probably more appropriately translated as (or at least less confusing if translated as) "one". Like "One can sleep on my couch." (meaning "one" in the sense of a person, but not any particular person). In fact, I do often see "man" translated as "one", and I even translate it that way myself once in a while when that sounds better to me or when I want to make sure the reader understands that I don't mean "you" as in "specifically 'you' the reader".
And of course "one" works fine in American English too, but it sounds a little stuffy.
In these cases there are two things to be done. One is to report it. The other is to turn to the community where you may find you are right so calm the frustration. Then as mentioned above use one for the real world and one for DL. This is after all a computer generated program and it will have its quirks.
It's not that I have anything against 'one'. I use it often e.g. 'One must have a bath once a week, whether one needs one or not' (but not in the peculiarly upper class British manner of referring to my own actions 'One must toddle, off. Toodle-oo'). It's just that a cannot think of an occasion in which a native speaker would say 'one can sleep on my sofa'. I might say 'My sofa can sleep one' to indicate that it can be used as a bed if necessary, or if I have a group of friends over I might say 'Somebody can sleep on the sofa' or 'One of you can sleep on the sofa'. I guess, an upper class British man might say it, but only reluctantly after a long discussion with his friend about the ongoing difficulties he is having with his wife, 'One can [always] sleep on the sofa'