Complex sentence: In the 1950s, Margaret's films won awards from major amateur contests in both America and Europe and by the 1960s she had become a highly regarded film competition judge, attending amateur film festivals around the world.
Split into simpler sentences: In the 1950s, Margaret's films won awards from major amateur contests in both America and Europe. By the 1960s Conneely had become a highly regarded film competition judge, attending amateur film festivals around the world.