It is known that great programmers almost consistently have very good lingual skills. All of the great programmers I know have a very good level of English. The famous computer scientist Edsger Dijkstra once commented that he preferred to hire English majors over Computer Science majors because the former made better programmers. If you see someone with an obviously broken English - don’t hire him! (I’m not talking about a few problems - these are common and people with an audible cognition are more susceptible to them. )