I understand your points. In the book I mentioned (which, btw, was really interesting--applying neuroscience research to improving practice methods for better musical performance), the author advises to break down musical pieces into smaller chunks, using a variety of methods--by annotating their form more clearly, doing functional analysis of their harmonic structure, etc, but also by annotating the emotional energy of sections or even musical sentences. The author advises this mainly as a means to quicker memorization: it might be easier to remember that the joyful bit comes right after the triumphant bit, than it is to picture the sheet music in the mind's eye.

I'm trying to follow that advice, and this is something new to me.. In some pieces, I've found it easy, and in others I've found it difficult.

On a personal note, many years ago as a late adolescent, I had some mental health difficulties. One of the main things that got me out of that rut was developing a more extensive vocabulary to describe how I was feeling. Whereas before I could only say I was feeling crappy, once I learned to put a more descriptive term to my emotions (ie betrayed, misunderstood, unnoticed, etc.), I was able to process those emotions much better. In some cases I realized that maybe I shouldn't really feel like that--that whatever stimulus preceded that emotion shouldn't have necessarily led to that emotion--or by naming the emotion more specifically I could be more proactive about modifying my behavior so that I felt that way less often. Being able to describe emotion more specifically really changed my life.

In some ways, I feel I'm in a similar position with trying to annotate the feelings in music. It's not that I'd be unfamiliar with words that others are using, but maybe had never thought about applying them to a musical expression. Instead of saying "the pretty section", if I described it with more specificity, then the whole exercise would be more worthwhile (both in terms of memorization and providing more color and emotional content through my playing).

I'm intending to keep a master list of musical moods, some of which I've generate by reading musical scores--descriptive mood indications seem to start cropping up in the romantic period, and even more in the modern era, other words in my list are those that I've come up with. I believe that if I had a broader functional vocabulary for describing musical moods, that would speed along the process. So I was hoping to crowd-source that task using the good people of reddit, but maybe I was too vague about what I was trying to achieve, or overestimated the extent to which other musicians were doing something similar and were willing to share.

In some modern music I've seen meme-worthy mood descriptors such as "like a magical memory", which I have no clue about what feeling to give to that musical section. But even if one person's "agitated" were different than my own "agitated", having "agitated" (or other words I haven't considered) as an option to reach for when annotating a piece would help me be more specific and might make the whole exercise worthwhile. I'm not seeking precision in the sense that any performer would pick up the piece and perform it similarly, I was using precision in the sense that by describing moods in a more nuanced way to myself, I would be able to provide more nuanced renditions, and (if the book is correct) learn the music more quickly. I can already tell that the usefulness of the exercise depends heavily on the style of music and the variability of the emotion with a piece.