Many of these Asian carriers would have crews that would be confused by the phrase "turn southbound". To "turn" makes sense but "southbound" is not commonly used in aviation. in my previous life in a Chinese carrier, the FO in the jumpseat would be using the radio and the crew in the front seats would respond accordingly. Many old timers have marginal English and i have seen confusion unfold rapidly when the young kids are translating a non standard term to the guy with his paw on the tiller, especially in US airspace where rt is commonly non standard. I suspect that Eva crews have a better grasp of English than the uncles from the mainland however a bit more precise controlling would have helped.