More and more of my job these days involves editing English written by non-native speakers. And it’s very enjoyable work.
But the more I think about it, it occurs to me that this is in many respects a translation exercise. We are taking thoughts expressed on paper and rewriting them for the sake of clarity. (Obviously we correct grammatical mistakes as we go along. Goes without saying.)
Whether French, German or non-native English is the starting point, it matters not.
This is what makes translators such good editors. We spend our lives taking thoughts and re-expressing them. When faced with a page of English that needs tightening up, we simply reapply the same process.
And like translation, solid subject-area expertise is vital when rewriting someone else’s English because these authors know the English terms of art inside out!