imho - the tolerance, the multi-ethnic character and political freedoms of the Commonwealth
Tolerance: For what? Jews?
Multi-Ethnic Character: BS. A bunch of different shades of white. Russians at least have Tuvans and Chukchi, etc. If you look at France or Italy closer you will also see a past of many ethnicities, not less than in Poland.
Political Freedoms: For oligarchs, and nobody else. You could find these kind of arrangements in the Lowlands, in the Merchant Republics of Italy, and other places.
I was just showing you how first of all the things you listed are not unique to Poland. However, I also think this is complete historic revisionism to view these things as somehow implicitly liberal (the Roman Empire is then very liberal, and the Mongol Empire). It's just you interpreting it that way, from today's vantage point. In reality - 95% of your liberal or centrist thought is Western in basis and very modern with no root in Polish history.
They insisted that, if the Orthodox and the Muslims could at one time have been tolerated alongside the Catholics
Hmph! Maybe I'm wrong - ha. This is interesting.