Fair. Unless new canon contradicts existing canon I just merge them, ymmv. As to the Raven Queen, she collects memories from across the multiverse for unknown reasons, why wouldn't she be interested in any memory sediment wherever it's located.Edit: suppose I should add that I'm assuming the sediment is from the natural memory stealing property of the river, though if I'm overlooking a 5e lore point then please feel free to point it out.
@Rukelnikov, specific exceptions can exist, that's not a problem.