The command editor is not very legible in dark mode:
Windows version of Rhino has advanced options. These options can change colors of the user interface. The Mac version of Rhino also has advanced options, but I do not know whether these options can change the colors.
Info about the advanced options in the Mac is here: Advanced
I don’t think this can be changed on the advanced options. If so, I don’t where to find it. The background I believe, is control by the Mac UI. I think McNeel should be able to fix text color on their end. It is indeed hard to look at, especially if you don’t have your monitor contrast turned to 11. I would not even mind if they were the same color as the palette heading text. Hope they update this in the future.