Standard disclaimer. I am not a lawyer, nor an Italian lawyer - and all this may be fine points of law beyond me.
However at first blush, what you quote does not seem to be at odds with what is in the Wikipedia article.
The citation Wikipedia uses for what I quoted is, "G. Di Federico, La Corte di cassazione: la giustizia come organizzazione, Laterza Editore, 1969."
A rather wooden Google-translation from the Italian version of Wikipedia puts it all thusly:
In the dozens of thread over the years where people have provided cites for their views, this seems to be in line with them.
The way the English version puts it is: "Although the Supreme Court of Cassation cannot overrule the trial court's interpretation of the evidence." This seems simply to be another way of saying that once a judicial fact is found in the lower court (as Mike1711 observed) the ISC may disagree with it, but it is bound by it.
Meaning that the M/B court could not disagree with evidence as found, it could only disagree with the way the evidence was assembled. As per the way the Chieffi court set it out in 2013, as well as the way the M/B court concluded in Section 10 of its report, the point is that the evidence in front of Nencini should not have resulted in a conviction, but an acquittal.
Perhaps the only relevant example to what you have noted above is if there was no legal grounds for (say) Nencini to have found something as factual, meaning that Nencini did not follow procedural law in establishing a fact.
Be all this as it may, there is no mechanism for the ISC to do fact-finding, so as to declare on it's own something to be factual. Vixen keeps implying that they do.
That's the issue.
There are items of raw evidence, and there are inferences that may be drawn from the raw items of evidence.
The CSC may rule, according to Italian procedural law, that the raw evidence was inadmissible, because it was obtained in a way contrary to law.
The CSC may rule, according to Italian procedural law, that the existence of a fact, inferred from circumstantial evidence, was an invalid inference, because the evidence was not serious, precise or consistent. This is what the Marasca CSC panel did in this case, for example, regarding the alleged DNA evidence on the knife blade and on the bra strap hook.
The CSC may rule, based upon its review of the interpretation of the evidence in the judgment (= grounds of the judgment), that the grounds are lacking, contradictory or clearly (= manifestly) illogical, and therefore annul those particular interpretations and even the entire judgment. Both the Chieffi CSC panel and the Marasca CSC panel made use of this provision of Italian procedural law.
The question is whether a CSC panel, in applying these procedural laws to review the interpretation of evidence, are doing so fairly rather than arbitrarily, from an objective viewpoint.
In the case of a final conviction brought before the ECHR as an alleged violation of rights, the ECHR may conduct a review of the judgment with regard to any arbitrariness.
For specificity, consider a hypothetical conviction that rests primarily on the denial of the prosecution providing evidence that DNA profiles were free from contamination and were otherwise obtained according to recognized international scientific standards. We can be confident that such a judgment of conviction was arbitrary. The Marasca CSC panel, in Sections 4.1 and 4.2 of their MR, relied on Italian procedural law CPP Article 606.1E (even if not specified) to make the following statements:
4.1...So when the central point of technical activity contains specialist genetic investigations, the contribution of investigative activity is ever more relevant; credible parameters of correctness must respect international standards of protocols, following fundamental rules of approach prescribed by the scientific community, on the basis of statistical and validated observations.
The rigorous respect of such methodical norms offers a conventional coefficient of acceptable credibility of such results, primarily linked to their reproducibility - namely the possibility of obtaining these results, and only these, reproduced with a constantly identical method and under identical conditions, according to fundamental empirical rules. ... This is typically leading to “objective” reality, reliable, verifiable and agreeable {= consistent?} ....
4.2 As will be seen, all of this is essentially missing from the present trial {that is, the Nencini judgment}.
This is an example of a CSC panel judging the evaluation of evidence (grounds of the judgment, CPP Article 606.1E) and the quality of the evidence used to infer a fact (CPP Article 192.2) in the decision that is being appealed.
The CSC does not hear new evidence; that is for the lower courts. But it can look at other court rulings from the CSC or the Constitutional Court, and at the legal or scientific literature.
What PGP and some PIP misunderstand is that the CSC indeed has the legal authority to review the evaluation and quality of evidence, whether or not evidence was admissible, and incorporating previous CSC or Constitutional Court decisions and legal and scientific literature into its judgments. Those activities are different from hearing new evidence.
The Wikipedia article appears to be incorrect and incomplete in its statement that the CSC does not interpret evidence. The CSC evaluates the lower court's interpretation of evidence, and can only do that by itself evaluating the documented evidence.
You point out that the Wikipedia article reference is from 1969. It's important to note that the CPP underwent some reforms beginning in 1988; I don't know if those reforms made the 1969 reference obsolete with respect to the authority of the CSC under current CPP Articles 606.1E or 192.
ETA: The Marasca CSC panel MR specifically mentions CPP Article 192 in its discussion of the DNA profile evidence in Section 7.1. This discussion continues into Section 7.2. Essentially, the Marasca CSC panel MR accepts the criticism that the DNA profiles of the knife blade and bra clasp had no scientific validity, and thus had no legal inculpatory significance. Here is one excerpt of their lengthy discussion: "Taking into account such considerations one really cannot see how the results of the genetic analysis – that were performed in violation of the recommendations for the protocols regarding the collection and storage – can be considered endowed of the characteristics of
seriousness and preciseness. {
Terms from CPP Article 192.2}"