Beginning from two premises — (1) the observable universe exists inside a Schwarzschild black hole, and (2) the physics inside the horizon is the same as outside — the Interior Observer (IO) framework predicts all major cosmological observables from one measured input (M_U = 4.50 × 10⁵³ kg) and one external constant (γ_BI = 0.2375 from Loop Quantum Gravity) with zero continuously fitted parameters. This paper confronts the IO framework's Schur definitive branch (Paper 29: H₀ = 68.91 km/s/Mpc, Ω_m = 0.336, Ω_k = −0.006, Ω_Λ = 0.670) with twenty independent observational tests spanning z = 0 to z = 1100. Results: five direct comparator wins over the Planck ΛCDM fixed-parameter reference, eight non-comparator confirmations, three ties, two indistinguishable, one mild loss, and one pre-registered future prediction — all with zero fitted framework parameters. Key findings include: five independent baryon probes each see the density predicted by the BDP α-ladder; the bare-branch local-clock age (19.181 Gyr) resolves the Methuselah paradox; and the Sandage-Loeb redshift drift is a falsifiable prediction testable by the ELT ANDES spectrograph.