Well, keep in mind, the Thirty Years War started 131 years after the Wars of the Roses ended, so you’re dealing with two eras. I wouldn’t call the Thirty Years War late medieval, and it’s honestly a lot more Early Modern than Renaissance, certainly by the end.
But yes, political structures are really weird in ASOIAF. As I discussed in my first Hollow Crowns essay, the Westerosi monarchy is really uneven. Its tax systems are way more advanced than its judicial powers, etc. The Great Councils of Westeros is a lot more like the Magnum Concilium of the Norman Kings than the Parliaments of the 13th and 14th centuries, let alone the Tudor Parliaments.