I believe correcting grammar mistakes should be permitted, however, with the limited option- range. As an example, if someone is not using any interpunctions and almost 25% of the question is misspelled in original content - this should be disqualified. I saw several questions and answers not containing single dot or capital letter. Considering that we have so many tools available to translate like: google translator etc etc bad English should not be so much problem. In case the question is unclear comments are available to ask further. Once you have more clear vision- I am sure your help will be appreciated. Nevertheless, If someone’s text is not 75% and above original should be not taken under consideration- it only means that person did not care and put effort into quality of the content. Moderators are here to guide and help- and this is great- but they are not your Personal assistant to clean all your mistakes and do your work.