Acceptance criteria for results comparison

Hi, Annex 21: 3.2 PQR: the analytical results from importation testing
should be compared with those in the Certificate of Analysis generated
by the third country manufacturer. Acceptance criteria for results comparison is also an agency requirement at the time of QP release in EU of FP manufactured in 3P country. There is no EU guideline (as far as I checked) that would suggest how such a criteria between sites could be set. Acceptance criteria at the time of Analytical Method Transfer are too tight to be set for commercial testing considering there is a time gap between testing at 3P site and testing at EU (typically between 1-4 months). Has anyone any idea/suggestion of the rationale based on which acceptance criteria for CQAs could be set? A statistical comparison between the results is not accepted by the agency as long as there is no acceptance criteria set (other than the Regulatory approved limits).