Julian was invited back to Sweden and he declined. It's not the job of Swedish authorities to fly all over the world to question people of interest, they would get nothing done.
1. No, Julian was the person of interest, he should come to the police, not the other way around. You claim the swedish prosecutor "was invited" but "declined" to question him where he wanted. Persons wanted for questioning regarding rape or any serious crime does not get to invite prosecutors where and when they want to have a conversation about it.
2. The Swedish court found that it was ok to do so because it was being dragged out, not that that it was their job.