I am writing an article with a senior colleague. Although English is not their first language, they keep re-writing the entire article in their own words.
I would not normally care, but the way he re-writes it is semi-grammatical and very hard to comprehend, so that I feel I have to change it back to something grammatical after I have figured out what he means. A week or two later, I will find that he has gone back to certain sections and re-written them so that they are in semi-grammatical English again.
I understand that language is not the main priority of a scientific article so as I say this would not normally bother me, but it is having an active effect on the ability of the paper to convey its results, as well as causing me work having to read and understand it to translate it back.
What is the easiest way to get around this issue without coming across as rude?
Edit: Unfortunately the manuscript was rejected by our first choice of journal and the referee comments suggest that the unclear writing style introduced by the supervisor was a contributing factor in this. I'll have to think carefully about how to re-write the manuscript when submitting to a more specialised journal.