I think that often when bad suggested edit is approved, it actually gets 1 or 2 rejection reviews. And I think it's incorrect to mark edit as approved if it has 3 approval and 2 rejection reviews as it shows that actually there is no agreement between reviewers.
Proposal: If less than e.g. 80% of reviewers agree on approval/rejection, new reviewers should be appointed.
If an edit gets 3 approval and 2 rejection reviews, it means only 60% of reviewers agree so additional reviewer(s) should be chosen. And so on until number of reviews with the same decision is 80% of the whole number of reviews.
If e.g. 20 people reviewed the edit and there is no consensus between them (i.e. less than 80% people agree on it), it should be flagged for moderator attention as it means that ordinary SO users can't agree on it.