Personally, I find the whole "reality is subjective" thing, a tad delusional. At least in an irl sense.
If I actually cut off someone's hand and slap them with it, even if they think they still have their hand and weren't slapped, they still were, and no matter what they think, I can just slap them again. Reality is inherently objective. It means what actually exists. You can perceive the hand as a ham, but it's still your hand or at least what is considered your hand.
Of course, within a fictional universe, things get more complicated. Nodoka actually talked about this a little:
So, within this world, I think what can be assumed to be intended to actually exist within this reality, should be considered "Real". Whatever isn't reasonably shown to actually exist within this reality is likely just a hallucination.