I have no idea, but I think its amazing they reverted the negative back to original cut. and reconformed it. after a new photochemical restoration. and cut out the Special Edition sections.
I’m surprised Fox even allowed the original to be tampered with in the 1990s because that was 20th Century Fox crown jewel. Disney protecting its investment it makes sense.
Plus we know that of all the O-negs Star Wars is the one that was in the worst shape in the 1990s. The fact they had to spend significant resources again to restore the film in the last number of years, it’s a culturally important work.
The special editions from 1997 were finished likely on interpositives, since they had to create at least some type of film element for 35mm printing at the time. But thankfully, the original negative itself wasn’t reconformed (and even if it was, Lucasfilm would’ve saved everything anyway).
Yes an interpositive would have been created, after the negative was restored and reconformed. Lucasfilm kept all of the inserts that were cut out of the negative, and those have been scanned in for the new restoration and cut back into the original negative, restoring it to its 1977 state.