Paper CCXLV (Throat-Threaded Magnetic Birefringence) issued forward prediction FP1: in hierarchical 2G+1G merger candidates the residual Delta = a_rem,measured - a_rem,CCLVI(eta) should additionally correlate with chi_p * M_tot^2 at rho_Pearson >= +0.30 with significance > 2.5 sigma on the O5 catalogue. CCLXIV pre-registered the top-10 |Delta| sub-population of its N = 146 GWTC-4.1 + GWTC-5.0 join as the natural target. We execute this test for the first time by selectively downloading 10 per-event combined PE data-release HDF5 files (Zenodo 17014085 v1 and 20348005 v9, 2.16 GB total) and extracting chi_p from LVK headline precessing-spin posteriors (C00:Mixed where present, else NRSur7dq4 / SEOBNRv5PHM). Univariate Pearson rho(Delta, chi_p * M^2) = +0.0439 on N = 10, with 95% bootstrap CI [-0.7861, +0.5208] (5000 resamples) crossing both zero and the CCXLV-FP1 +0.30 threshold. The selected sub-population has Delta span 0.081 (compressed by the |Delta|-selection) but chi_p * M^2 span 100x; the within-sample correlation rho(Delta, chi_eff) = +0.885 remains strong, demonstrating that chi_eff drives the residual within the selected sample while the additional chi_p * M^2 term sits below the noise floor at N = 10. Multivariate decomposition Delta = a + b * chi_eff + c * chi_p * M^2 yields b = +0.4119 (matching the CCLXIV population OLS slope +0.3716 to within 11%), c = +4.74e-7 (sign matches CCXLV-FP1; magnitude is a plausible sub-dominant contribution), and R^2 = 0.83. CCXLV-FP1 is NOT falsified by this test. The methodology is established. Three predictions: CCLXVI-P1 pre-registers the full-population partial correlation rho_partial(Delta, chi_p * M^2 | chi_eff) > +0.20 at > 2 sigma after extracting chi_p for the remaining 136 events (~28 GB additional download); CCLXVI-P2 chi_p median distribution should peak near 0.3-0.4 reflecting prior-dominated regime at moderate SNR; CCLXVI-P3 multivariate chi_eff coefficient must remain within 20% of +0.372 across data extractions. Honest scope: N = 10 too small for definitive conclusion; CCXLV-FP1 framed for O5 catalogue (~SNR 30) while we test on O4a/O4b (~SNR 12); selection geometry compresses Delta dynamic range. Framework count: 267 numbered papers.Part of the One-Octonion Brane-Bulk Framework series. Anchor DOI: 10.5281/zenodo.19120873. Community: one-octonion-brane-bulk. Author: Bharathi Dasan Jagadeesan, M.D., University of Minnesota. ORCID: 0000-0002-1143-941X.