As you can understand, it is impossible for us to test each game to completion. If you do come up to a point in a game where Fenrir causes the game to crash, please do let us know by creating a ticket here.
It is planned to make Fenrir 100% compatible with the Redump set, but we also want to be honest with you and while there are only a handful of games that have trouble with Fenrir, we won't declare Fenrir 100% compatible until it truly is tested by the community.