I don't know if there's more to this rabbit hole, but a few self-reported cases (placebo effect?!) and a theory with some gaping holes don't seem to me like "well documented cases".

If there are physical changes you can expect some effect on personality - say if a new heart is able to more efficiently transfer blood the patient might find herself more prone to physical activity. Or a better kidney and liver might affect food preferences. New blood type might offer have some wider effect but even that's a still very much questionable field of research.

To latch onto the example given in all your links, there are no taste receptors in the heart and neither is there any indication that memories are saved in the heart. Spinal cord - yes, especially if it's about movement. But not in organs like the heart which give much more basic input and have far fewer connections to the rest of the neural network. There is no chicken nugget and beer neutral network linked to the heart - and if there was, chances are any organ transplant would have severed them.

It's been suggested that gut microbes affect mental functioning - maybe a surgery/transplant could affect the immune system (not to mention immunosuppressive drugs would be a given, right?) which in turn would affect which microbes thrive, and therefore personality.