I think it could be an issue. Dozens/hundreds/thousands of people interview at Google. If I was interviewing for a programming position, and they were misspelling words in the e-mails and mangling their English, and English language communication was important in the job (as it has been for every job I've had), that would be a red flag. With so many others of a probably equivalent competence interviewing, it wouldn't take many red flags for them to be passed on for an offer.