It's an excellent game, hope you get to try it out even if you don't pick it for this particular venture.
Forgive some unsolicited advice, but if you ever do get around to it, the bit that was trickiest for us to wrap our heads around was the Touchstone role. They don't have quite as many mechanics to interact with as Power and Perspective, so it can be easy for them to feel a bit sidelined.
The truth is, though, Touchstone wields an enormous amount of power. Played right, they decide if the Kingdom lives or dies. Power and Perspective should absolutely be trying as hard as they can to court/persuade/win over/cater to Touchstone at every turn, because that is the only way to get the people on your side. Perspective could be throwing out softball predictions with a clear right and wrong answer, but all Touchstone has to do is throw their weight behind the "wrong" choice and it still turns into an agonising dilemma for Power. Can't rule over ashes.
I think you've done well with the concept! Solid history without being too ornate, lots of open room for development and questions answered, and sounds like you've already got ideas about how to highlight with mechanics.
The only piece of advice I would give is, in addition to thinking about leaving hooks open for the DM to work into the story, also consider the other direction: how is your character going to be moved, compelled, and changed by the broad strokes of the adventure they are going to get into and the companions they are going to be adventuring with? How can this character help set up other characters to do "their thing"? I've found the games I've played in to only be improved by having those dialogues with the DM and other players up front