The foams are just placed on the wave crests using a simple height calculation. The material is set into a plane surface which moves with the camera in order to make you think the is infinite, when in reality it is not, and plane has its triangles with more density near camera and less triangles far away. I think the result we are seeing here happens because the camera used with Sequencer is not the one repositioning the plane, meaning you will have less triangles depending on the spot you are in, meaning you will lose height for the waves since there are less triangles to make the displacement look better.
I will check the code and try to tell you if is precisely whats going on and how to workaround . My first thought without taking a look at it, is for you to save the character attached camera position and drive its position with Sequencer for later you recover the original position.