My main point was that many of PJ's changes were not matters of interpretation, and the Faramir incident was my absolute proof of that. You can't deny that point. I didn't mention that particular incident with the confusion aspect in mind. I've already listed several PJ additions that were confusing to viewers in
this post.
But since you brought it up
the Faramir/Osgiliath episode also adds something confusing to the story. It introduces the infamous "Nazgul moment", which you must admit was horrible planning.
The Nazgul finds the hobbit with the Ring right outside Mordor and yet we're to believe that this information never gets to Sauron??
During this scene my friend exclaimed, "Oh no! Sauron knows where the Ring is now!"
But based on later events in the movie, Sauron obviously didn't know. It's as if PJ threw in the scene with absolutely no thought about the repercussions.
Every event has (or should have) an effect on the rest of the story. In other words, if Aragorn were to get his armed chopped off in the first film, that event should cause him to appear without an arm for the rest of the movie. If you add something, you must follow that change through to the end and make sure that the rest of the story reflects the addition you made. That is the danger in putting in things that did not actually happen.