I think some of my personal confusion in the beginning came from interpreting what the family was saying about Nora's abilities (which may have come from extended family and I understand the parents have now distanced themselves from these statements). At first, I thought she just had learning delays, so the insistence that it was a kidnapping seemed odd. Then, it seemed like the family was saying that her condition was such that she was all but physically unable to have left the room and maneuvered down the stairs on her own, so abduction just about had to be the only option. But, abduction from a room with numerous other people planned within a few hours of their arrival? That seemed so odd. Stranger abduction is pretty rare and in a foreign location like this and invovling foreigh nations, it seems even less likely, so the idea that it was all planned within hours of their arrival and carried out by some abductor bold enough to break into their room or somehow lure her out without alerting anyone else just defies belief. It isn't impossible, but it certainly doesn't seem likely.
However, now, it seems like it was more that they were saying that it wasn't physically impossible for her to have left on her own, just completely out of character, which I can understand in their minds made it seem almost impossible. After all, they wouldn't put her in a second story bedroom, with the bathroom and another bed option on the first floor, if she was truly physically incapable of leaving the room on her own. They probably wouldn't have chosen this vacation spot if she was so severely physically limited. They couldn't have been worried that if they put her on the first floor she would leave b/c they obviously never thought that was a serious concern since it would be so out of character. So I really think a lot of my initial confusion was because I accepted the idea that she was far more physically limited than she may actually have been, making abduction almost the only possible scenario, when really, the parents were maybe saying it wasn't physically impossible, just so wildly out of character for her that the didn't believe it was possible. When I take the physical impossibility away, by far the most likely scenario is that she left on her own for a hundred possible reasons that we will never know and got tragically lost in an unfamiliar place.