How to interpret reviews that focus only on grammar mistakes but a decision of "consider after major changes"?
Possibilities:
- There are so many grammar and spelling mistakes in the manuscript that they pointed out a few by way of example and sent it back for English language editing before a full review. Given the quality of writing in the question, this seems unlikely.
- There is a missing review that was not sent to you that has asked for more major revisions. Sometimes this happens if the reviewer uploaded their comments as a file. Log into the submission web site and see if you can find any extra review files associated with your manuscript.
- The editor accidentally clicked the wrong button in the editing software and meant to send it for minor revision. This seems possible, but it is very strange that the reviewers did not comment on the results at all, and suggests a very poor review process.
- The editor doesn't like the paper very much themself and has sent it back hoping for a major revision, but has been too lazy to provide review comments that would help.
- The editor is particularly annoyed by grammatical errors and sent it back for a small number of minor errors to be corrected before being willing to send it to reviewers.
To me, the "missing review" hypothesis seems most likely. I would check the web site, and if you don't find another review file, contact the editor to clarify whether the grammatical changes you mention are really the only changes required.
Nobody here can guess the probability of your paper being accepted. Make sure you didn't miss a part of the comments somewhere when downloading them. If there are indeed only such comments, correct the spelling and grammar and re-submit.
It means there are plenty of grammatical mistakes in your manuscript those must be confusing the actual message of your work or what you want to say. So need to be corrected before taking any decision. By the way, if it grammatical correction only, then high chances of getting accepted. Good Luck!!