Don't get me wrong, I know 4 languages, which means I keep forgetting words in ones I am not using, and it gets a bit awkward to speak in it after a while. But

Don't get me wrong, I know 4 languages, which means I keep forgetting words in ones I am not using, and it gets a bit awkward to speak in it after a while. But you know what? I speak in it anyway. How else will I improve my language skills? The other thing is, they're going to university in USA. Most of their studies will (likely) be in English, so by not picking up English, they are hurting not only their studies, but future career prospects. Unless, of course, they also have Chinese employees, that only employ Chinese people, which does happen where I live (Australia).