I think the main reason for making a difference is to challenge all the interpretations put upon this material by literalist Christians who take it as read that Adam and Eve were the first two humans, or symbolise early humanity. It's an attempt to wake such people up to the possibility of deeper, more esoteric interpretations. Such Christians have a very limited understanding of the nature of the cosmos, all the various levels, and especially their weird ideas about the soul. This translation is therefore a good wake-up call. Once that has been accepted, we can then go on to ask the deeper questions that you mention here.

I certainly believe that the text is, or seems to be, saying that Eve and Adam didn't have to fall, thus that they had free will. That does suggest that the fall was not part of the plan, so my question would be rather, what would the universe have been if the fall hadn't happened. The text doesn't seem to elaborate on that. However, I agree that the intelligent universe would have to accommodate itself to the fall, and make adjustments, so to speak. This may be the deeper meaning of Jesus's saying that he came to forgive sins. He is sometimes described as the second Adam. Perhaps it was our original sin that he came to forgive.