Some of my initial transmission stuff was mentioned here:
got a good deal on a new 2020 touring last weekend. about 150 miles since then. :)
www.driveaccord.net
I think it's gotten a little better over time, and with more AT Fluid changes. I'm doing another scheduled ATF 2.0 change this week when the temp gets a bit warmer. It's not a complicated process, but you have to take the bottom plate off, etc.
The transmission began making noise in Sport mode while decelerating on twisty mountain roads. I probably noticed it in the 130,000 to 150,000 mile timeframe. It's a slight transmission "growling"/"bearing pressure" sound. (Likely worn gears)
One day, closer to 170,000 miles, I was leaving Denver and headed South which had me around Larkspur where you are climbing in elevation for a while. I pulled off of the highway after being in traffic and slower 30 MPH driving for about an hour and the transmission jerked real hard with a loud thump. I think it got too hot and the friction plates were stuck. The slow changing from Park to Reverse has happened to varying degrees ever since. Again, no appreciable metal in the fluid or anything. It took a few days for the transmission to feel a little less unhappy but we made it home to NC just fine. I changed ATF2.0 a few days later and now it's almost normal except for the slow shift to reverse. (I wonder if something is out of place in the valve body)
Nothing else has really changed with it since. There's definitely some wear in there at this point. I never shy away from Sport mode and spirited driving in the mountains though and it makes a little more noise now. I still need to locate a low-mileage AT to rebuild.
I didn't change spark plugs until around 190,000 and they were just starting to seem worn out. I've used 3 bottles of Gumout Regane High Mileage Fuel System Cleaner for a few weeks which "felt" like it helped a little. I might use more soon.
I have not had any issues at all with the turbo. I keep up with my oil and filter changes so the bearing should be doing okay. I use Pennzoil Ultra-Platinum 0w20 (rated really well by Project Farm as I recall) and a Purolator PL-14610 Oil filter. (I change the filter every time even though the maintenance schedule says you don't have to)
I'm not really concerned about a specific failure at this point. I suspect it will continue to wear out at a steady rate and I will have to put some money into it to keep it going. It's paid off now though.
I wish the 2023's had a 2.0 10-speed option!!! I prefer the new taillights.