"playing by ear and trial and error (mostly the latter).

That's probably the utterly WORST way to learn the instrument"

I hope not, because it's exactly what I tell my beginner students to do. Reading music directly on to an Anglo is quite tricky, since the instrument has a different logic to, say, a piano or a fiddle. I'm not a great fan of complicated schemes of symbols either, since you have to indicate which button, which end, which finger and which bellows direction. It becomes very laborious and inserts a layer of extra complication between brain and music.