However, the author decided to rollback.
What is my proper/polite behaviour in these circumstances?
Perhaps, I am exaggerating the importance of my edits.
What I would do is the following (consider the context of an edit war between OP and another user):
Edit Q in good faith trying to improve the post, like you did.
If OP rolls it back (and it bothers you), try leaving a comment explaining why you think the edit is valid (it may happen OP rolled it back because he/she did not agree with something about the edit). Wait.
If nothing happens (no reply from OP), then roll the original edit back. Wait to see if it will be rolled back again.
If it does, do what Midavalo suggested
raise a flag for moderator to review the edits and rollback, to avoid getting into an edit/rollback war.
As an alternative (or if OP rolls the edit back again), consider casting a down vote for lacking of readability as a possible proxy for 'unclear, does not show research effort, and/or not useful' (which is the tooltip that appears when hovering the down vote arrow).
The order of topics is a suggestion; it depends on how much time and energy one would want to spend on an edit war.