Nicely said my friend, nicely said. I agree 100%I learned Goodbye Pork Pie Hat from the Jazz Workshop chart. It's been a tough little sucker for me. There are some really nice chords, which were new to me. Stretches my ear like a really hip little see-saw, rocking back and forth with these rich chords.
Jazz Workshop, I'm told was affiliated with Charles Mingus back in the day. It's a highly playable version, based in Eb. I think Beck does it in D.
You go on youtube and various folks play it all over the place different keys, tempos, arrangements. That's what happens to standards I guess. I've never yet found a recorded version that follows the chart exactly. I have that Joni show recorded at the Santa Barbara County Bowl,w/Jaco/Matheny, I think it's on there and I'll check it out.
Oh and Joni Mitchell? She's a badass if there ever was one. Master artist, just a sick concentration of talent in that soul, and she owes nothing to nobody. Well done Joni, one hell of a life of art! People will be celebrating her gifts for many, many decades, probably longer.