I'm intrigued.
If Poland does something dickish internally, what does that have to do with the UKs EU membership?
When the UK sold Typhoon fighter jets to Saudi Arabia, would you expect the Poles (or any other EU member) to start wringing their hands over their own EU membership?
Well, no, because Poland is pretty supportive of an imperialist approach to foreign policy, cf their strong support for the Afghan and Iraq fiascos, so why would they worry about the UK doing such a thing?
Besides, you've picked a foreign-policy issue. That's not analogous to what a country does domestically.
Incidentally, why did you baulk at the term 'superstate'? What else would you call the EU? It has many of the trappings of a state (a legislature, laws, free-movement, even a foreign minister) and involves a commitment to 'ever closer union'.
Are you scared of the term because you lack confidence that the populace actually want that?
Personally I don't see it as a negative term, I'm OK with the idea of a superstate, I'm all in favour of European union, just not necessarily
this European Union.