You can find a 'reading' of the chord structure to Autumn Gold in 'Aiming For the Heart', a lovely hardback small format book of Andy's songs, published in Germany in 1988 - ISBN 3-923555-01-6 (the number might have changed since 2007?) Introduction by Paul Brady and illustrations by Eamonn O'Doherty (of 'The Northern Fiddler' fame).
As is the case with many of Andy's arrangements, the chords are a guide to his subtle, almost counterpoint, style. No point writing them out for you here, as there is a lot of information in the 'reading' (e.g. Cm9 with B-flat in the bass) which you would do well to look at.
Look for the book, and listen to the record. There's a transcription of Smecano Horo in the book too, a grand bonus!