On Dr Jayaram, I would not judge his reliability as a witness based on that evidence only, but also from:
The many changes he made to his account of Child K over time: the case where he claimed he had found Lucy Letby doing nothing to help a child in crisis
https://www.reddit.com/r/LucyLetbyTrials/s/ZEtSYHRyZT (long but a great read)
The eventual revelation that he had emailed to say that Lucy Letby had in fact called him for help
https://archive.is/Krydn (Unherd)
The gradual evolution of his memory of child A's distinctive rash, which he failed to mention not only in his medical notes, but also to the coroner's court, after he had read Lee's article, when specifically asked to help the court with any further information
(The coroner's inquest came up at Lucy Letby's trial, so the Court of Appeal had this information as well as the information on notes, but for whatever reason doesn't mention it. I would say that that omission doesn't reflect well on them. There was indeed another reason apart from the medical notes adduced to question Jayaram's reliability, and that was the evidence he had given in another court of law, the coroner's court)
https://www.reddit.com/r/LucyLetbyTrials/s/wyE0ZX8uu4
I suspect that one of the issues that the CPS must have weighed when considering new charges is whether his testimony, in old or new cases, could now stand up in court. It doesn't seem right that she can remain in prison for the rest of her life with this man's testimony having played so large a part in her conviction.