"立体派艺术家" can be translated into English as "Cubist artists".
Here, "Cubist" refers to the artistic style of Cubism, which was pioneered by artists like Pablo Picasso and Georges Braque in the early 20th century. "Artists" is the plural form of "artist," indicating multiple individuals who practice this style.
So, when referring to artists who are associated with or practice Cubism, you can use the term "Cubist artists."