The reason you can't find the Cursed Ring of Braccus Rex in the root template manager is that it's a local object, an instance of the root template LOOT_Gold_Ring_A fa4c97b6-4543-4346-a132-ccb8d82f23cc, placed in the Fort Joy level.
As an alternative to Fumihiko's reaction, there are OnTurn and ObjectTurnStarted events in behaviourscript and Story, respectively, to which you can react.
