Honestly, I am in the same boat as you with a lot of the quirks with carplay. I use it maybe 10% of the time and purely for navigation as the Lucid navigation cant be trusted 100% of the time and when I need to be somewhere for work well I can't waste any time. Yesterday I drove down the Tucson from Phx. Theres a dead spot on my trip and as expected, carplay disconnected (not a big deal to me, I understand why it does it. This is not the problem). On reconnect (which I manually had to force), all my audio was now playing through my phone yet the carplay GUI was still going just without audio. I dealt with it and got to my destination.
On the way home though, carplay still had no audio but unfortunately once I hit that deadzone, carplay would not come back. I sat messing with the settings for about 15 minutes while I was driving but no matter what I did, I couldnt get carplay back. I tried toggling wifi on my phone multiple times, I went to settings and tried to manually start carplay, after about 60 seconds of "Starting carplay" it eventually just failed with no error message. It never came back so the last 45 minutes, I used on Lucid navigation. Sure I could have pulled over on the highway at 10:00 PM to restart the car and tinker with it to get it back but I shouldnt have to.
I've also had the issue in which Tidal starts playing while I am on the phone and scares the crap out of me. I'm also constantly frustrated by my music resetting whatever playlist I was listening to. Dont get my started on the music GUI (regardless of the service). Unfortunately, I have also gotten enough work calls while I am on the road in which customers cannot hear me but I can hear them that I have resorted to always picking up the phone and changing the source to my phone.
Same with the phone key you mentioned. I got my antennas replaced which fixed the key fob unlocking abilities. My phone key has never been all that great though and I have come to terms with carrying the key fob.
Sure all of these may be fixed temporarily by re-pairing my phone or restarting the car or factory resetting the car but I've done all of those things in the past and these issues always come back. Not to mention, when the mobile app update came out, I already removed my phone from the car side and removed all pointers to the car from my phone side. I restarted the car and my phone, and then re-connected my phone to the car. That was just last week. I dont post here much anymore as I think maybe I am too critical on the car but I have got to the point where I am content with these downsides but also realistic about these downsides when talking to people about the car. Im not going to demand Lucid fix these things because that doesn't do anything. But I do want to share that you are not alone with these issues and frustrations. Honestly, you'll have to decide if the downsides are worth the upsides and if you can live with the flaws the car has.