"We travel to the high, blue mountains; we rest there."
Translation:A magas, kék hegyekhez utazunk; ott pihenünk.
That would place an unnecessary emphasis on us, making it sound like "it is us who travel there, not some other people". Nevertheless, I guess it could be argued that it is acceptable, as the English sentence can also be stressed that way. "WE travel to the .... ".
Yeah, I think that Hungarian just has a lot of nuances which are difficult to translate directly into English, due to its free (or flexible, rather) word order. I know that this makes gauging sentences as correct really difficult for languages such as Hungarian on Duolingo, as you can see with the number of native Hungarian speakers who have been complaining about some of the questions.
Odapihenünk sounds a little weird, because pihen is usually a pretty motionless action, but oda is a directive prefix. Nevertheless you could interpret it as "we lie down there and rest".
But it doesn't work in this sentence because you're resting at some place, after you have already moved in the first part of the sentence.
I put utazunk first and the rest of the sentence was identical. Was that wrong? The computer wouldn't accept it.
It is a possible translation, but having a (non-prefixed) verb in the first spot tends to sound a bit weird.
Also, it's better here to have the verb after the mountains. This way you're putting focus on the mountains, which you are referencing in the second clause.