Re wording of medical letters:
"Under review" is the normal parlance when you have a patient who has regular follow-up appointments for the same condition to check on progression, treatment etc etc. The doctor is reviewing the patient; the patient is under review.
Patronising language - well, "charming gentleman" etc is a bit, isn't it! I think that nowadays doctors tend to be a little less flowery in their letters to each other. Also, of course, everyone has different styles of writing. I personally wouldn't even clock this, never mind read anything into it.
"Despite" (etc) - I think this is probably just clumsy. Again, I wouldn't read anything into this - I can't say if others would.
Semi-secret codes that doctors use between each other? How very dare you 🤐😂 Many years ago, there was no right for a patient to read their records and you should see some of the plain speaking used in old hospital letters! Now that copies of letters are cc'd to the patient, everyone is very much more circumspect. There are always ways to phrase things when you want to imply something without spelling it out, of course.
That 2019 letter reads to me as though it's been written by someone who is so used to medical jargon and parlance that they've forgotten how to parse a simple sentence. As I said, it's clumsy and clunky. My understanding however of the second half of the first para is that the consultant is rethinking the diagnosis, but in the absence of any confirmatory tests (maybe none is available), hasn't got a firm alternative diagnosis to offer.
But TW was clearly not terminally ill at that point!