I think most people wouldn't even notice the geographic anomalies in a map. We would cuz that's our thing but 99.9999% of the world doesn't do what we do. That's why you see messed up rivers and misplaced deserts. I can let a northern desert slide but I can't let the rivers go. For those of us who do this sort of thing, when we see the oddball terrain you have to explain it somehow and it usually falls back on magic of some sort. I consider falling back on magic to explain things as a weak argument as I tend to favor physics and science to explain the terrain. When magic comes in to play I tend to take the Belgaratth method...you don't mess with mother nature because the amount of magic and power needed to do something is so staggeringly large it would kill the person. Sure a god might be able to do something willy-nilly but that's an even weaker argument than magic. For me, I can only suspend my disbelief so much...small areas of oddball terrain or slightly misplaced terrain. But as I said earlier, I don't think that anyone outside of The Guild would ever notice such things.