How to play Autumn Leaves in the style of Bach

[Christian Miller]

You could at least drop to accurate historical pitch

Come to think of it Ted drops the pitch too.

[Jonah]

from my reading what’s quite interesting is it is not at all clear whether 18th century composers understood these as separate keys, which kind of reinforces your point. They are just natural mutations of the basic key (also relative minor of course.) But to discuss that further would require descent into the world of hexachordal solfege and tbh I’m not sure if I really quite understand that. Mi and Fa, fa and mi. As Bach said.

Yes, of course.
But they definitely used modulation as a semantic element of language whichever terminology they used.
It is tge basis of tge firm as fundamental fir expressing yge contents.
I think it is impossible not to hear it (otherwise what is there to hear left .. texture?)

Quite clear, established and definite modulation to dominant key
and back absolutely the same essentially as it will be 100-150 years later. With very clear cadences.
No need for hexachords (and really they do not work there even).

The painters do not necessarily think litterally proportions and composition but it dies not mean that they do not use.

And here is very typical form... modulation to dominant key at the end of 1st section.
The 2nd section starts in dominant key but shifts to subdomibant area creating a feeling of 'development section' with its unstable character and tfe returns to tonic.

Basically in my opinion this form is ambivalent. Formally it is 2 sections but in reality there are 3 sections.

Here... (key is Cm) fist very smooth modulation to relative major Eb, and immediately 2 bar modulation to dominant Gm... and then the material is almost exactly repeated in a new key after that unstable subdominant area section with modulation back to Cm

Major sign of conscious and very expressive usage of modulation is repeating material in new key in every example I gave.

Later on classicism will break this ambivalence and bring it to a sonata firm with its definite proportions of form and relations of keys

[Jonah]

but AL does modulate to the relative major and back - just as Bach would do in a minor key piece

Well it is not modulation really.. modulation in my understanding is something more definite. It requires full cadence in a new key - often even twice.
And here it is just a slight deviation in the middle of the phrase.

[Peter C]

Had momentary dyslexia and read how to play A L backwards

[Jonah]

Had momentary dyslexia and read how to play A L backwards

Important skill for reverse looping