Paper rejection probability after two round of major revision.
In general, few editors would allow for several rounds of resubmission unless they would like to publish the paper. Therefore, the probability of eventual acceptance should be much higher than the base acceptance rate at the journal.

With regards to the status updates: "with editor" means that the editor is about to look at your resubmission and make a decision on whether to send it out to referees. "Under review" means that reviewers have been assigned. In some cases, it does not mean that the reviewers have actually agreed to reviewing. The switch back to "with editor" suggests that the reviewer has either declined to review the paper again or has completed the review. In the former case, expect the paper to switch back to "under review", in the latter case expect to hear from the editor soon.