Living conditions in prison in Sweden are better than when they lived in freedom in Afghanistan. I would not be surprised if after serving the sentence, they again commit some other crime, not to return to Afghanistan. I would sent them to jail.
I'm not sure about Swedish prisons, but I still remember when Breivik went on a hunger strike in Norway until he got a PS3
https://www.rt.com/news/340356-breivik-verdict-playstation-torture/If these boys are grown enough to rape, they're grown enough to fight
They should be deported