Fine post - a lot is packed in here and I'm not sure if I've unpacked enough to comment usefully. Also I hesitate to launch into my first reaction to any use of "Real" "Realism" etc. Frequently, larger implications of these words are not particularly helpful to whatever discussion is at hand.
But as you note in one of these rcent posts, one's perspective plays an important part in how one sees "the national interest". Point of view is in fact a necessary component of rationality and for this reason alone the convergence of the rational and the real is open to question. The problem with POV is that it proliferates.
In some Buddhist discussions of emptiness, the term "valid cognition (of conventional reality)"is used to cover much of the territory we might ordinary cover with naive realism. So discusiion in terms of the valid cognition of Polish national interests can proceed without making ontological claims.
So we can then discuss a time priviledged perspective of Polish national interests covering the first arrival of humans in Middle Europe to the present or even near future. Separatly, if we wish, we could use a space priveledged perspective focussing of the array of objects (broadly defined) existing right now in some kind of cause/effect repose to Poland. It my be that the resulting discsussions end up with differing notions of Polish national interests - the defense of borders for instance might be viewed differently.
All that is required in the valid cognition structure is that the participants to the discussion agree the resulting arguments start from defensible cognitions.
I'm afraid this is as far as I can take this now. I'm uncertain how useful it is. At any rate, these recent posts are quite good.