Yes. One dares presume that the reason we're given this sentence is that it's a natural sounding way to express this in portuguese. The natural sounding English way of expressing the sentiment should be accepted.
If course the other possibility is also, sadly likely--that it's just as awkward in Portuguese, but it was the best someone could do under a deadline to give us some practice with the word revisão.
Yes, that would work. It should be noted that the literal translation, "The text is without revision", is, in fact, proper English, but if you were to say it to someone they would more than likely look at you as if you had two heads on account of it sounding very archaic and antiquated.
The following are all a lot more natural:
"The text is unrevised." "The text is not (isn't) revised." "The text is unedited." "The text is not (isn't) edited." "The text is unreviewed." "The text is not (isn't) reviewed." "The text has not (hasn't) been revised." "The text has not (hasn't) been edited." "The text has not (hasn't) been reviewed."
I hope that helps!
Once again the choice is between Duolinguese and English. I keep thinking I know how to play the Duolingo game. In this case it worked. They wanted Duolinguese, not English as the translation for the Portuguese sentence. And I see from the comments that after five years the Duolingo text remains unrevised.