The use of the term "understanding" in the quote you mentioned is a claim about metaphysics, not cognitive capacity.
From Merriam-Webster:
cognitive: as in reasonable; of, relating to, or involving conscious mental activities (such as thinking, *understanding*, learning, and remembering)
From Merriam-Webster:
cognitive: as in reasonable; of, relating to, or involving conscious mental activities (such as thinking, *understanding*, learning, and remembering)