Yes. It's most important for YOU to understand what you're communicating, regardless of the method of communication; whether that's English, Latin, sign language, stick figures, etc. That said, if you were working with a spirit of Chinese origin for example, and you translated what you wanted to say into Chinese, that action could potentially reinforce your work and make it more effective. Not because the spirits wouldn't have understood you otherwise, but because you invested more effort into the whole thing.