basically having stair in the lower part makes it harder to aim, and altho the wood plank slabs are there to keep u from exiting it i feel that those somewhat get in the way too. tbh the best windlass designs are on erebor (they use a fencepost) and if u could somehow design the front like those to allow better aiming that would be fantastic. also a house kinda obstructs the ballista's aim too and that's annoying