LONDON — An exquisite rhythm rolls across the sheer mass of Emily Kam Kngwarray’s paintings, produced in prolific bursts of creativity between 1980 and 1996, the last decade and a half of her life. As she worked at the forefront of a movement that sought to translate millennia-old Aboriginal cultural traditions onto media such as acrylic, canvas, and batik, much of her oeuvre is marked by a strong visual cohesion.