It seems like the castle roof is incorrectly affected by roof height, instead lifting up a portion of the middle when attempting to change height. Also, it is impossible to fix because the roof height is locked permanently from going down below one. One is unable to fix by returning the value to 0.
Have you tried setting the slope direction to all four cardinal directions instead of just E/W? I haven’t build with this tool yet myself so I can’t comment on the fix
It is impossible to set slope direction on castle roofs, as two - either north and south or east and west - directions only are highlighted at a time. If I were to try and click on N or S, it would just activate the other one too and rotate the roof.