Hwa's slide is never negative on block unless you do it without cancelling into it. s.B, s.A or whatever cancelled into slide will leave you at least a +0, if not better. And I also wouldn't say that crouch-blocking Hwa is a great plan, as his hyperhop D WILL cross you up, leading to midscreen crossup pressure strings. His light normals also hit crouchers and give him massive advantage on block, giving him amazing pressure and grab setups.