I have rooted various Mulberry. I treat my Mulberry cuttings the same as figs, cups of perilite in humidity bin with bottom heat, and low strength feritgation.
Persian has had the lowest success rate, followed by Pakistani. Best success has been with Morus alba such as Shangri la, and various proven unknowns. Guessing off the cuff, 30% with Persian and 40% Pakistani success rate, and 60-70% with others.
Success to me is fully rooted and continuing to leaf out, and up-potted to gallon container.
Good Luck