I just checked Ancient Mai and the Gatekeeper, and the book estimates them to be in the upper teens. I understand that this is a starting point and that people are free to change it up to suit their games, but the book puts the line for High Council membership around that point. Which is what I remember it being roughly, and what I was talking about above when I say that you can hit that level in your game.
As for Harry, I don't think he's in the 20s as of Changes. Assuming that 1 book is 1 story, that gives him a point of Refresh every few books. If it would be every 3rd book, he's around 14. If it's every other, he's around 16. So I'll call it 15 for a nice middle road. So he's powerful, but not quite on par with a High Council member.
Then again, I play a lot of Exalted, and I like Nobilis, so the idea of the PCs becoming some of the most powerful things in the setting doesn't frighten me. I sort of like the idea that -- after a year or two of regular weekly games -- the PCs might be in line to join the High Council, or maybe be able to take the Council as part of their schemes.