I am glad you liked it!
I had the same doubts about the movement patterns. They are deterministic but except for red triangle & square hard to predict. I often run the level to see how the shapes move and then make a guess how the correct wall placement could be.
I am thinking about adding tooltips on the shapes that show the movement pattern. But I am not sure if that is actually an improvement. Maybe it is more fun to guess & retry than to do the brain twisting calculations what will actually happen?