Well, the petitioner would consider it successful if the annulment is granted. Also, please note that there is a pre-screening done at the parish level with the pastor. A lot of people who would have filed a petition are told that they would not have adequate grounds for annulment and the petition never gets submitted.
It reminds me of the district attorney’s office. While it is true that a suspect is innocent until proven guilty, a DA does not usually waste time and money on a weak case with little chance of obtaining a conviction, as resources are scarce.
I would also note that until pastors start taking the bull by the horns and properly preparing couples for marriage, a lot of mercy is going to be needed in granting annulments. If a pastor looks the other way as couples cohabit and live like people who have no religion, you can expect that there will be many ceremonies at which God is not really invited, despite the trappings of religiosity. I hope that what Pope Francis is saying is that pastors are going to be getting a lot more picky and making couples understand the commitment they are making and having them practice self-sacrifice and delayed gratification before they take the plunge.
Success is measured by the petitioner only? What about the spouse who contested the annulment, like Sheila Rauch Kennedy?