OK so I’ll get to it. I think Cap is the MC. Tony is the IC.
Starting from the beginning, I feel the roles need to be flipped. Cap is still Fixed Attitude and Tony Situation.
Cap isn’t actively trying to get anyone to do anything. He just cares about his friend.
Tony on the other hand shows the team a digital dossier on the murdered boy I Sokovia. To influence their decision. Widow see’s the sense in his argument and immediately takes sides.
And with the theory, the IC is usually bothered with influencing the MC the most. Which is why Tony keeps going on about Cap signing the Accords at least once every act. Cap refuses, and Tony gets frustrated,and so he tries again and again. Steadfast resolve.
And with the RS being in psychology it makes sense. It has to do with Friendships. Tony and Cap predominantly. We see the downward spiral here. Cap and Bucky had no deviation or drama per se, so it isn’t so much about them.
Also for a movie so grand, we do have much more screen time with Cap. Usually it’s the IC that stays offscreen the most.
We see Tony directly influencing Spiderman. Cap was never shown trying to convince anybody. Night wing called on his behalf.
Hope this lends some clarity?