While I completely agree that the switch functions backwards to what other manufacturers are doing, but I understand why Kia is doing this. If you have a playlist open on your screen, pushing down on the switch to go to next track makes sense. It would be good if Hyundai/Kia gave customers options to choose the functionality but I highly doubt it is going to happen. It would be faster to get used to the function.

As for reversing the switch, the left switch module will have to be taken apart and does not look that simple. Good luck and as always, when working with steering wheel, don't blow the airbag.
Edit: The switch part is #96710-S9030SA1 and around $100 to replace if you mess up.