I’m assuming that everything that we see in MoR is from within a single consistent (albeit fictional) history
I agree with this assumption: that’s why MoR only shows you the consistent history of the usage of Timeturners. The Timeturner itself is the only point of possible divergence from consistent history (assuming no magic lets us mess with causality, although it seems like Weasley’s “opposite reaction wards” at least have a chance), and EY is writing a story about a rationalist Harry Potter, not a story about wizards using Timeturners, so he won’t bother to show all the inconsistent histories.
And “inconsistent histories” from the perspective of a consistent history is a contradiction in terms; it is no wonder it clashes with the meanings of real, exists, and so forth.
I agree with this assumption: that’s why MoR only shows you the consistent history of the usage of Timeturners. The Timeturner itself is the only point of possible divergence from consistent history (assuming no magic lets us mess with causality, although it seems like Weasley’s “opposite reaction wards” at least have a chance), and EY is writing a story about a rationalist Harry Potter, not a story about wizards using Timeturners, so he won’t bother to show all the inconsistent histories.
And “inconsistent histories” from the perspective of a consistent history is a contradiction in terms; it is no wonder it clashes with the meanings of real, exists, and so forth.