the article also says
Lucas’ tweaks to the print began with the very first theatrical rerelease of Star Wars in 1981. Until now, the studio has only permitted the screening of various Special Editions. BFI negotiated with Disney and Lucasfilm for the rights for a back-to-back screening on the festival’s opening night. This particular BFI print was stored for four decades at a temperature of 23 degrees Fahrenheit to preserve its quality.
Which is incorrect. The changes first happened in June 1977 with both a few SFX shots being redone and the mono mix being released, not to mention the 35mm and 70mm mixes that were released simultaneously