So, I was wondering if there were any 'missing' nations compared to historical 17th Century. i checked a map for 1648 (post-Treaty of Westphalia, which ended the 30-years War).
Working from the west:
Portugal: subsumed into Castille?
Spanish Kingdoms: Castille.
Scotland: Highland Marches
Kingdom of France: Montaigne
Holy Roman Empire: Eisen
Dutch Republic: part of Vestenmannavnjar?
Kingdom of Denmark: part of Vestenmannavnjar
Swiss: covered by Eisen? maybe not.
Italian City-states: Vodacce.
Kingdom of Sweden: also part of Vestenmannavnjar
Polish-Lithuanian Commonwealth: Sarmatian Commonwealth
Hungary? Partly outside the HRE, but not under the Ottomans: Eisen??
Transylvania / Wallachia/ Moldova, Satrpies of the Ottomans?: In crescent Empire book?
Tsardom of Russia: Ussura
This gives 3 possibilites: Portugal, separate from Castille; Switzerland, free from Eisen; Hungary.