The only thing I have to say is that I think the GOUT is the key to finding out what TESB is supposed to look like. When I found a nice color correction for ANH and applied those settings to ROTJ, it came out very close to the grindhouse ROTJ scan. So I’m assuming that if you have a correction for ANH that works for ROTJ, that using that on the GOUT for TESB will get you something close to the real colors. Enough to guide a shot by shot regrade and possibly provide a basic correction that works for most scenes.
We actually have a reasonable color reference for TESB in Puggo Strikes Back. Surprisingly the colors of the 1997 SE home video release is a pretty good match for these colors. As for the samples poita shows us, Hoth is quite a bit more blue than the GOUT would suggest, as are the interiors of the Super Stardestroyer. However, as NeverarGreat mentioned, we will hopefully soon be able to see the theatrical colors when poita scans the unfaded 1980 print he has bought.