What do you think of the time aspect? Specifically a Seer of Time? And do all time players have to have some interest in music?

Time is a valuable thing. :D

A Seer of Time might study ancient things, or might have an intuitive understanding of things like the alpha timeline and how it functions. They might have a grasp on the nature of inevitability, or death. They might know a thing or two about narrative progressions, or archaeology, or any of a number of subjects, and use that knowledge both to guide their allies, and to perform straggering miracles and tricks. They are somewhat likely to learn how to shoot those weird rainbowy time lasers.

Time has an association with music, but they are not synonymous. Aradia may have music box land and a music box time machine, but there’s no real signs she herself is into music much. And on the flipside, there’s plenty of non-Time heroes into music (for instance, all of the beta kids)