When you review a suggested edit and select "Reject and Edit" the following reason gets displayed:
This edit did not correct critical issues with the post - view the revision history to see what should have been changed.
Apparently this reason is automatically applied to every "Reject and Edit"; there is no place to select a different rejection reason. Yet this particular reason is only accurate in cases where the problem actually was that the suggested edit did not fix other critical issues. But it is equally possible that an edit would be rejected because it fixed things that shouldn't have been fixed. In such a case this rejection reason is quite misleading. It makes it seem as if the problem with the suggested edit was that it didn't do enough when in fact the problem was just the opposite – it did too much.
A suggested edit might make 10 changes, 5 of which are appropriate and 5 of which are inappropriate. In such a case I don't think reviewers should use the "Improve Edit" selection, because that lends credence to the suggested edit when in fact it contained inappropriate changes. Indeed, the very reason of "did not correct critical issues..." implies that the edit should be rejected even though it may have contained some appropriate changes.
So in essence, there does not seem to be a good way to review edits that contain some appropriate changes and some inappropriate changes. You can't approve the edit because it contains inappropriate changes, but rejecting the edit sends a message that there was more that should have been changed which is oftentimes very misleading.
As I was writing this I saw this related feature-request from seven years ago which doesn't seem to have gone anywhere which asks for the ability to use a custom rejection reason. That would certainly solve my issue, but I don't even need to go that far. I think that simply removing the words "This edit did not correct critical issues with the post" would suffice. The automatic reason would then simply say:
View the revision history to see what should have been changed.
(maybe add "shouldn't" as well)
The suggester could then simply view the revision history to see what the problem with the suggestion was, and this would be made even easier if the reviewer explains the problem in the edit summary.
Basically, I don't think it matters that much what the new way to "Reject and Edit" would be, as long as it does not contain a default clause which can often be inaccurate and misleading.