James Cameron's "Avatar: The Way of Water" is over three hours long. That's more than 190 minutes of screen time in which every frame of every second demands a high fidelity of CGI. It also requires music because movies are eerie without an underscore to inform the emotional current. For Cameron's first excursion into Pandora, James Horner composed. With prior credits such as "Braveheart" and Cameron's own "Titanic," Horner's involvement was practically guaranteed. Unfortunately, Horner lost...