The effective communication principle in communicating with someone whose primary language is different from the other is letting them "SEE". it's in the environmental factor that people tend to remember and communicate effectively through what they see for about 30% effective.
Principles 3,4, and 5 would be especially important. If you and your communication partner do not speak the same language, nonverbal messages would be very important. It would also be vital to carefully listen and respond appropriately and finally, you would certainly want to adapt your message (use simple terms, short sentences etc...) so that it could easily be understood by someone who speaks a different language than you do.
I would assess this info in the context of the work expected from them. Are they building websites for you? While the site appearance does reflect somewhat on their image, it may have little or nothing to do with their value otherwise.
