While consideration of previous crimes is not allowed, I think actions taken in the course of the currently tried crimes are allowed to be considered. So even though the jury decided that Holmes’ actions did not meet the requirements for the crimes against the patients, the judge can still consider the impact her actions had on the patients when deciding the sentences of the crimes she was convicted on.
Was this in Italy after the war?
Nah. And it wasn’t in black and white either!
To add to what others have already said (jury instructions are very important, are often - and should be - relied upon by jurors in their deliberations, and are not infrequently an issue on appeal), it’s true that there aren’t “any surprises in them” in that counsel know what the judge is going to be saying. By that point they’ve had the chance to provide draft language to the court, and to argue why this instruction ought to be given and why that one shouldn’t be. But once the judge starts reading them to the jury, the lawyers know exactly what she’s going to say.