Region
Notre-Dame map
Rooms inside the cathedral
Named parts are the Undercroft, West Triforium, East Gallery, Great Organ Room, Stained Glass Gallery, La Flèche, the Chapel, the Choir, and the Room of the Four Virtues. Mirrors of Life are listed for the Undercroft, West Triforium, and East Gallery.
Searches for 'all notes' line up with clues and the melody sheets, not with a currency. The upper tower is the platforming on La Flèche, where the Concerto sheet sits. A step-by-step of that jump is not written down in the sources, so I am not drawing a route I have not verified.
What the rooms are for
The Great Organ is the puzzle. The Choir is Death's card fight. The Chapel is Arthur once the prerequisites line up. The central stained glass is the Doppelganger once the Four Virtues are done. The East Gallery holds a sage sigil that needs Smash, double jump, and a dash from the top of the organ.
What I ran into
I kept almost calling the melody sheets 'notes' in the collectible sense. They are clues. Saying that in the first screen is the difference between sending someone hunting books and sending them to the organ.
Questions
Where are the melody sheets?
Fugue in the Great Organ Room, Sonata via the Stained Glass Gallery, Concerto at the top of La Flèche.
Where is the upper tower?
La Flèche. The exact jump sequence is not published in the sources I used.