Not sure where else to post this:
Producer’s personal production schedule indicates a full ROTJ mono mix made in between 35mm Dolby Stereo and 6 track.
So this indicates:
35mm DS mix, optical stereo track tested to ensure proper playback in the event of no Dolby decoding or decoder failure, full mono mix done from the dialogue music and effects stems, 6 track music and effects only mixed track, and the 70mm Dolby 6 track mix in addition to printing the blowups. So this is some official documentation indicating they were still doing mono at LFL post-SW, ESB and Raiders. It wouldn’t surprise me if a mono Temple mix is floating around too.
BTW this making of ROTJ paperback is fine reading.