I would just add that I'd worry about this connection if you're not reasonably mobile.

You won't have to run but it will be a bit of a walk. Air Nostrum CRJs land at the very north end of T4 main so you will have to walk to the center part to get the train to T4S and then US flights leave from the very north end of T4S so will have to make that walk, too.

At passport control if you have a tight connection they will help you to skip the queue.