Z.-W. Sun has recently announced a determinant-based proof that Catalan’s constant G is irrational. We verify Sun’s framework and identify one genuine gap in the final quadraticledger: the factorial contributes a 2-adic term which is not absorbed by the odd-prime positive-part bridge. When this term is included, thefinal B^2 coefficient becomes positive, and the contradiction 0 < |N_B| < 1 cannot be derived.We propose a minimal correction: replace the monomial reference columns ir in Sun’s determinant by binomial coefficient columns. The finite-difference transform then diagonalizes the reference block with unit pivots, and F_B disappears entirely from the determinant formula. All odd-prime constants—the odd small-prime constant c_odd, the middle-prime integral Λ_mid, and the large-prime improvement 83/2400—are unchanged. The final coefficient becomes strictly negative. The contradiction 0 < |N_B| < 1 for a nonzero integer N_B is thenrestored. We also note a harmless indexing typo in Sun’s rank theorem and confirm that withthe corrected indexing the proof is valid. A supplementary SageMath verification suite coversevery quantitative claim of the paper.