Um, a couple of things:
1. I might be misreading but I don't follow your ID setting sequences. The manual for this car spells out the standard approach shown below:
Do you hear the audio cue? Also you only cycle power on at the start. I appreciate that this means reaching under the car to revert to "RUN" but I think that if you have heard the cue the ID has been set.
2. I have a couple of Legacy StationSounds diners and have not had problems setting the ID. One of these cars was partly defective because a board was shorted as the result of a wire pinched at the factory. So the RCDR was bad but after being replaced under warranty it worked correctly and has ever since. Yes, there was the 2019 fiasco about certain diesel engines not being able to keep an ID AND I have one steamer from that period that has the same problem. So it's a known issue but I have not heard of it affecting sound control boards.
