I generally avoid discussion of theory since it's not critical to my everyday functioning in music.

However....

When you look at the written sheet music, you are given everything you need to know. Assuming you can read the music. You have the key signature which tells you the key and indicates the sharps or flats that are in the music. Knowing that, you play the correct notes.

If a note is intended to be one of the "avoid notes" but the composer intends you to play it, that too is indicated by use of an accidental.... a sharp or flat symbol placed immediately in front of that note.

Chord symbols are there in sheet music for other folks, mainly guitar players who can not read the notes on the staff. If you're using them to play the song, your accuracy is going to be diminished from someone who can read the music.

I took piano lessons for a number of years and had a piano teacher who could look at a piece of music she had never seen before and tell you all about that particular piece of music..... key, chords, inversions of the chords, whether it was a major or a minor key and so on...

If you are having difficulty with something, before you make the assumption that the system is broken or incomplete, learn more about it because 99% of the time, it's not a broken or incomplete system, it's a lack of knowledge. This was brought home to me in a real way when I bought a pistol and shot it.... I thought the sights were off.... the gunsmith at the store told me to "go learn the right way to shoot before you start messing with the sights".... and he was correct. It was me lacking the knowledge.... so too with music and long established musical systems be it the Nashville system or do, re, mi, or whatever else.... all those systems were developed over time to allow people to use them to play music that someone else had composed and to do it relatively accurately.

I'm not trying to bust on you..... just saying that perhaps a bit more study with a teacher or mentor who understands them would be helpful. If you have a teacher who doesn't understand those systems, there's no way they can teach their students the proper use of those systems.

You can find my music at:
www.herbhartley.com
Add nothing that adds nothing to the music.
You can make excuses or you can make progress but not both.

The magic you are looking for is in the work you are avoiding.