The Four of Cups is a good reminder that there’s no single right way to think about elemental correspondences. Everyone’s relationship with the elements is personal.
Just like how different readers approach the same cards differently, some use reversals, some don’t, your take on whether Swords are Air or Fire depends on what works for you. Both approaches can give you meaningful readings. The cards speak differently to each person. Your elemental system just needs to make sense in your own practice.