>>10649341I'd go the opposite direction. Ignore the idea of adding dark lines and add highlights instead.
I think you did go a bit overboard with the shading, particularly from the front. Shadows should have directionality, and it doesn't make a ton of sense for the back to be very darkly shaded with the front being shaded heavily as well. I like how the back looks, and personally would just tone down the front to be thinner dark areas.