Aquinas’ explanations of how God “knows” can be an answer to this - when God knows something, desiring it to be really present (not just in his ideas or concepts or understanding), then He “wills” it to be, and his Spirit proceeds. The Eucharist is not a thing done by God alone, but by the Spirit inspiring the Church to “do this in remembrance of me” and then joining Christ to this bread and wine as his Body and Blood. When the Soul and Divinity of Christ is thus united with this Body and Blood, then what God knows within himself (the presense of Christ united to this bread and wine to feed us) is also an objective reality, and God is pleased, happy.
It is just as an architect who has a plan or idea of a building internally in his understanding, he “knows” the building within himself, then he has a builder follow his plan so that the building is not just in his understanding but is a real object external to his understanding but matching his understanding - and he is happy, pleased, at “peace”, at “rest” with his knowing - what was good and true in his understanding is good and true in objective reality. In his “understanding” he not only visualized the design of a building, but he visualized it being real outside his thinking, real in the real world.
No one, however, will be able to know the reality of the real presence of Christ by a reasonable explanation - it is a “revealed” truth. We have heard and we believe. But as a revealed truth (that we “know” because we trust the one revealing it to us - the Church) it then can be analyzed by the one who believes it. The only ones who can grasp the reality of “transubstatiation” are those who already believe that the bread and wine are now Christ’s Body and Blood. Without the revelation of Christ in the eucharist, and “knowing it is real”, there can be no reasoning about bread, wine, substance, accidence, etc., that would lead one to conclude the real presence or conclude transubstatiation. But when you start out with “faith”, knowing it is real, then the thinking about what it all means begins to make sense.
John Martin