I’m assuming the error of The Beginning: Making Episode I documentary getting put onto the disc in letterboxed 4:3 (as opposed to 16:9 as it is on the second disc of the TPM dvd from 2001) never got fixed?

Unless of course that was done intentionally for some weird reason (maybe so the lower resolution wouldn’t be as obvious? I doubt they finished it in anything higher than SD all the way back in 2001, and most of the footage is from ‘97 to ‘99 anyway). But if your documentary is already formatted for 16:9 tv then I don’t know why you wouldn’t keep it that way.