Then to me, there's really no real complaint here. No one on this site is likely ever going to be happy with the authentication program, because the program really isn't designed for people like us. We already know what to look for, and already have more expertise than the authenticators do. You are going to see threads here and elsewhere when things go wrong, and everyone will dump on this program and call it stupid.
There won't be hundreds/thousands more threads when things go right, because when it goes right there's nothing to talk about. eBay wouldn't be doing this just for fun, so clearly there has been a major issue with fakes getting through and people getting burned. For every one "error" like this, I'm guessing many fakes will be caught. This program isn't going away, because for what it was intended to do, it basically works.
This thread proves that despite it going through and this being missed, the sale was reversed and you were made whole. Sure it would have been better if they had caught the dent, but people are human and make mistakes. The back-up of buyer protection still kicked in.