The aCRF page numbers in the define.xml are there to allow reviewers to easily navigate to the correct page in the aCRF (unfortunately to-be-artificially created) PDF.
Most important is that when the reviewer clicks on the hyperlink in the "view" of the define.xml (so usually, the define.html), the PDF viewer opens at the correct page.
That is also why the Define-XML standard allows to provide a "bookmark" (in the aCRF) rather than a page number (PDFPageRef/@Type='NamedDestination') as an alternative.
When reporting aCRF page numbers in the Define, should the page numbers be the PDF page numbers or the page numbers printed on the aCRF?