As I said earlier: “But that COULD take more than seven jati or births within those seven bhava. There is no stated limit to number of jati within a given bhava.”
There are only two bhava involved here, 7 births in each bhava. That is what is meant by: “..Seven from here, seven from there”.
He was born a human 7 times before being born in the deva realm. It appears that he died very early in each of those. Even if one lives for a day that a birth.
Then he was had a cuti-patisandhi transition to the deva bhava. Those latter 7 births were within the same deva realm. Of course, there is no gandhabba state or going into a womb in the deva realm, so when a deva dies — and born in the same realm — that deva seems to just to be born in a different “location”.
– So, there had been only one bhava change (i.e., cuit-patisandhi).