Hi Vincent, I wondered if your last post was an anomaly or the first of many. Nice to see you back again.
I thought Amazon explicitly used the print edition page count where available; I don't know what they do if there is no print edition, or if there are multiple print editions. It's what they appeared to do with my books - and note that my print books are done through Lightning Source (Ingram) not Amazon. The Kobo page counts are significantly higher, I think because my print edition uses a relatively small font.