I'm afraid to inform that's not quite the case, the only option of jetway that is being offered for selection is one of them that is not the most suitable for the plane type and position. Then, what happens is that the selected jetway crashes over another one (which in turn is the most suitable, since it's closer to the plane and unobstructed).
Sorry, but I can only repeat and confirm that nothing is "wrong" with GSX, but you must understand how it works.
First, about the jetways crossing into each other. This can only happen if you use the automatic servicing option, which will auto-dock jetways or, if you dock them manually, if you cross them intentionally.
GSX cannot possibly know in advance if jetways might cross into each other, that's why they might cross if you use auto-docking and it won't prevent you do cross them. As explained in other threads when asked about this, to prevent jetways to cross, you should configure one jetway that would only solve on ONE door, and another jetway that would only solve on ANOTHER door.
Also, I've seen several cases where a multiple selection of jetways is made available for the user to choose.
That's normal and it's also normal you won't always see this. GSX will only show a menu with jetways that will solve depending on that particular combination of airplane, doors, jetway model and parking positions. And, if there's only ONE jetway that would solve to ONE door, it will even SKIP the menu because, of course, it would be silly to offer a menu with only 1 choice.