If you think the science is solid, treat the authors how you would like to be treated.
How have people helped you to be a better writer?
I would start my review by highlighting the strengths and why you think the science should be published.
Then, provide positive and constructive suggestions.
Here’s an example of what I might include in a review (as long as it is all true):
I found this manuscript to be timely and presenting relevant for this journal. The topics of X, Y, and Z fit well into the mission and… <provide 1-2 paragraph summary of the research>.
Technically, the work seems solid, although I would like to see (revision points here in a paragraph.
Lastly, the writing had some common mistakes. I have provided some suggestions to help the authors. For example, the authors consistently did not use consistence tense throughout the paper and .
As specific examples include:Line 102: Update “researchers writes” to be “researchers wrote” and check throughout.
Lines 107-108: Contains a run-on sentence. Please consider shortening to be
For these types of reviews, invest as much time as you think appropriate given your own schedule and ability to help.
Edit: Even if you think the science is unsound, please treat others the way you want to be treated. But, do not worry as much about the writing in the review.
Focus on the underlying science.