I would be interested to see the same viz with a 'less granular unit' if that makes sense. Sorry I'm chronically weak on terminology lol - but instead of having the model classify every sentence, maybe every paragraph. It is so granular as it is now that it's hard to read intuitively, but I also suspect mood is more meaningful in literature over longer units than a single sentence on average.

I have never used ML models except for janky bespoke corpus analytics software in college linguistics classes so if there are computational reasons this approach wouldn't work then I get that.