PSG was not lucky enough playing Dortmund in both first and second leg, because assuming those balls that hit the bar of the goal post were goals, we will not be seeing Dortmund in the finals, but as luck is involved in all games, that was what brought Dortmund to the finals.
When it comes to luck, I think that Real Madrid are more lucky than Dortmund since football history, and when it comes to quality football, I believe that Real Madrid has it more than Dortmund, also when it comes to quality players, they have it all. This is why I don't think that there will be any magic that will make Dortmund win Real Madrid.
If you assume that football depends on luck or unluck, of course I don't think we will see PSG in the semi-finals, but instead Barcelona deserves to be in the semi-finals against Dortmund, but a defeat is still a defeat in football, there's nothing we need to argue after the referee blew the final whistle of the match, I think PSG deserved this defeat because they were just lucky to be able to qualify for the semifinals if fate was a factor in qualifying, as you said if Dortmund were lucky after several kicks from PSG players hit the crossbar and goal post at that time, but apart from that, of course both teams played quite impressively in that match and indeed a small mistake in a crucial match would certainly result in defeat.
Currently Dortmund and Madrid are in the final, Madrid will be the favorites in this match considering their performance and experience in the Champions League, but still Dortmund will not be easily beaten because Dortmund has made thorough preparations to face Madrid, I think the Dortmund coach is not a stupid coach who will just face Madrid without any special preparation or strategy in the final match later.