Justice Lui begins this opinion by saying:
"This case presents the following issue: May an expert
relate as true the case-specific content of documents which were
neither admitted into evidence nor shown to be covered by a
hearsay exception?"
Well, yeah. When you put it that way, the question sort of answers itself, doesn't it?
As indeed the Court of Appeal so holds. "We conclude under People v. Sanchez (2016)
63 Cal.4th 665, 684–686 (Sanchez), that such testimony is
inadmissible."
Framing the question in a particular manner sometimes tells you all you need to know.