I've finally done it! I got the tree to 100%, first try! It only took me... Multiple weeks.
I think this is the perfect level of difficulty for a puzzle game; Whenever I got completely stuck, there was another path to go down that ended up either knocking some branch out that was blocking my path, or giving my brain enough of a break to look at other puzzles with fresh eyes. The last few non-blood names were satisfyingly intuitive to all place down at once!
I also LOVE the notebook mechanic, though my one request would be to have either more tabs or scrolling/separate pages under one tab. I ended up having just enough tabs to finish, but some of my writing ended up eye-achingly small due to lack of space.
Would love to see a sequel / sister game!