Catholic religion teachers teach catechism incorrectly all the time, literally every one I’ve had has contradicted another. I have my understanding of transubstantiation from conversations with priests and franciscan friars. The whole concept requires that no physical change occurs. The essence or concept of the bread and wine are infused magically with Jesus divinity and his new covenant, it’s a whole thing, but anyone genuinely thinking cannibalism is fundamentally misunderstanding an admittedly contradictory concept.