I am quite aware of that. I’m also aware not all costumes and props are identical. Not all the information from the R2 builder’s club is accurate. In one of my conversations with one person, I was told in AHN R2’s blue panels should be dark purple - always. And while I do think the first ones were painted as they say, in the bright sunlight it washed the purple out and it was very blue. There are some shots in ANH where the sun makes them almost royal blue. So if you make R2 completely consistent throughout the film, you’d get it wrong. Ben’s brown cloak seems almost gray at times on Tatooine, but in Mos Eisley and on the Death Star it is dark brown (as in the costume photo above). So you have different costumes and different lighting and the variations are endless.

In the scene we have been discussing, I think it is more important to get the hard colors right - the rocks, dirt, and flesh tones. I think R2’s blue panels should be dark and lean to the purple side, Ben’s cloak to the gray side, and Luke’s pants should have a slight green cast, but those aren’t as important.