I’m on a pc without anything earlier than RM10 but I note that @thejerrybryan says that the spouses of lineage aunts and uncles were listed on screen as uncles and aunts in earlier versions. What is new is the extension of "spouse of " a relative to more distant ones.
What has bamboozled me for a while this afternoon was that almost the very first spouse of an uncle I looked at is not categorised as anything, either in the sidebar or in the Kinship List. But that’s the only one among the spouses of my six first uncles and aunts who does not. Admittedly, this is a play database file that has undergone lots of operations but RM shows nothing weird in the main views and Edit Person windows.
Good luck with your sqlite queries. I look forward to seeing them.