The new 70mm track is by Hairy_Hen. You can see what’s new here: https://originaltrilogy.com/topic/Star-Wars-1977-70mm-sound-mix-recreation-stereo-and-51-versions-now-available/id/11348/page/27#1207818

The new 35mm stereo track is by schorman13. The one on the latest version of DE (2.5) was done by Hairy_Hen, which fixed a number of audio drop outs and issues from the laserdisc. They are both primarily sourced from the Japanese digital laserdisc, but the one done by schorman13 uses the newly available optical audio to determine which dropouts and crackling were present in the original theatrical version, and which ones were not for maximum accuracy.
It should sound very similar to all the previous versions of the 1977 35mm stereo track that have been released, but it’s the most accurate to what was heard in theaters.