I've realized it's kinda hard to play Caetlynn in the way I first thought, so I might give her powers a few of her "upgrades" early on just to make her a bit less useful. (After all, the story goes by the idea that she's been in a party before, so she's probably got at least enough experience to get this ability) She can now very loosely categorize what spell she needs, can sense what spell is going to come up, and can reroll her next spell once every one hour per category. These categories are Attack, Utility, Buff, and Debuff. The spells are still random, but if she has a free action she can potentially attempt to narrow it down enough so it could actually be possible for her to find something that can pertain to something she needs both in and out of combat.
Actually, I might consider giving her a system similar to an older character of mine, Steve Karmer, and allow her to "store" spells in the small charms on the bracelet, similar to Steve's P.RAM. Maybe one of the more magically inclined party members can analyze the bracelet and discover that function.