Hello Feierstarter, welcome to TM. I think that the Morgan three-wheeler is a very emotional affair of the heart and certainly a lot of fun, I personally have not experienced one. Yes, there are also reports of this or that lack of reliability. It's a matter of weighing and you can make your own impression in the three wheeler section of this forum. That is exactly where I would post all your questions again exactly as you asked them here in the Welcome Forum, because not all 3 wheeler drivers always read the Welcome Forum. If you have personal experience with car or motorcycle repairs this could be a good advantage so you don't have to go to the garage for all the annoying little things.
To sum it up, most 3wheeler drivers have so much fun with their Morgan that they are happy to put up with a few niggles. There are a few things to consider when buying. First and foremost, the year of manufacture and whether any improvements have been made to the frame of the vehicle, depending on the year of manufacture. This is the one point I would like to emphasize now, because this is already very important to consider before! the purchase. As I said, the guys in the 3 wheel forum know much better than I can.
Good luck with your research here in the forum and also for your later purchase!