Hi Juice-Tin,
This is a great problem to tackle and there are many different approaches one might take. For example, you can try making a Spline Actor that follows your River and then just use one Audio Component that moves to the closest point on the Spline Actor to your player.
However, with that approach, you will want to solve the problem for when the sound is actually two sources from the perspective of the player, for example, at the mouth of the C the two tips of the river will act as two sources, if you’re in the center of the C, it will act like one continuous source that spreads across your sound field except on the east side of the C.