Are non penetrative sex practices risky for contracting leprosy? E.g.: female (active) to male (passive) masturbation without condom, fellatio.

Maybe, but low risk. Any personal contact (kissing, skin contact, etc) can transmit leprosy. This includes sex, both penetrating and non penetrating, but probably no more often than other contact. Fortunately, leprosy is quite hard to transmit. Most household and sexual contacts (e.g. spouses) never catch it themselves. I suggest you discuss it with the doctor or clinic caring for the person with leprosy.