The location of the outlet pipe at the wall may make it very difficult to clear any future blockage. Also, such designs tend to have small leakage on the wall and that current position means it's difficult to spot any leakage, and repair it.

Have you sought second opinion on relocating the inlet and outlet pipes? It certainly sounds strange to a layman like me to have the pipes buried deep inside the wall? As it will be hidden by the cabinet, you don't need to retile after relocating them which helps save some cost.