The fact that Rush was able to communicate better in Korean was often listed as a reason Rush seemed to spend so much time working around Impact rather than the bottom half of the map. It was easier and faster to set up plays.
It reminds me of Spring split Fnatic, where the jungler and the top lane would speak Korean to each other, the bottom lane would talk in French to each other and Febiven was often left on a communication island in the early game.