When Kylo was on Mustafar and he has killed everyone, he turns around sharply as if he has heard something call to him. I know you’ve added sounds to when he picks up the wayfinder but would it possible for the sounds be extended and for them to start just before he quickly turns.
I once tried adding audible Sith whispers at that precise moment. This would also create an instant relation between the whispers and the wayfinder for the audience, considering they later guide Rey to the dagger and the Emperor’s wayfinder.