The same judge instructed the jury that they did not need to be certain of the murder method.
So, if you believe Letby harmed one child - let's say by overfeeding which could easily be accidental in the qualities claimed, and wasn't proved ...
then you may assume without further evidence (all of which hinges on a specific method in trial and conviction) that she harmed or murdered any infant involved in the trial.
This is far far too low a standard for a safe conviction