Subject: Oh hey! I had this once!
Author:
Posted on: 2013-03-04 04:33:00 UTC
I think I'll just relate my experience to you, as I had it with a very similar situation that occurred to me.
I was actually going to spork a Mass Effect fanfic that had a Gary Stu and a REALLY bad Mary Sue (they had managed to impress Aria for doing nothing, a batarian took them in because the plot demanded it, and the Sue had a pair of holographic roller skates *shudder*). But she actually expressed interest in rewriting it, and when I went in to review it she actually took my criticisms to heart when she rewrote it. (And trust me, when she did rewrite it, the end result was much improved over the original version.)
So what I'd do is this: I'd review it, and then ask about that in a PM depending on how the author responds to the points you bring up in your review.
Those are my two cents on it, anyway.