This is an interesting take. Given the performance of the tranny, it doesn't seem to be anything wrong. I dont really want to take it to the dealer for analysis, but I guess its that or dig into ECU.
It's the dirty little secret in the electronics field that the weakest link in most electronically controlled devices when it comes to discrete components is electrolytic capacitors.
They contain a gel or grease like filling that over time dries out and will either cause the capacitor to swell and burst leaking the gel onto the circuit board or just dry up and stop functioning all together in any case an out of spec electrolytic cap will cause all sorts of weird symptoms that will look like any number of other problems like bad grounds, faulty power, ect. If you can get the cover off the ECU a nice peek will usually find exploded caps, but if you can soldier it might just be better to replace all of these cap types.
Might be a dozen at most, and they cost very little.