All Word Power's copy editors are native English speakers. Copy that has been translated by a non-native English speaker typically contains many inaccuracies in grammar and vocabulary. It also fails to take into account matters of style, and may fall into the trap of using inappropriate slang, or expressions that simply don't make sense.
The same can happen if you use computer software that offers instant translation. Such software has its place, but it cannot be relied upon to produce professional results. Try a simple test. Input this piece of English text into a typical online automatic translator:
Now translate it into another language, select and copy the result, paste it into the input box and translate it back into English:
The AlanDuncan's the international pot hall li with it includes the wide scope of the enterprise
The differences between a first-class translation and a mediocre one will not always be so obvious. But they will still be there. A non-native English speaker might not appreciate these differences. Many of the people you deal with will.
Follow this link for examples of Word Power's many areas of copy editing expertise.