We confront General Coherence Field Theory (GCFT) with three current cosmological frontiers using only its established structure and public data, and report where it lands on each. (I) Lyman-α forest: the model-derived y⁴ acoustic-island source amplifies the high-redshift halo mass function (89–243× at z=25) while staying invisible to compressed statistics (the CH24/LaCE emulator shifts ≤0.05%); five feature-resolving treatments — a linear FGPA projection against the DESI DR1 P1D full covariance (Δχ²=165–419), nonlinear and bounded lognormal–FGPA flux models, and a published full-hydrodynamic primordial-magnetic-field analogue — all disfavour it. (II) Cosmic birefringence: established GCFT forbids the observed isotropic rotation (β=0.30°±0.11°, Planck PR4) on three independent grounds, predicting β=0; a calibration-resolved detection falsifies it. (III) Dynamical dark energy: the coherence field as spintessence obeys ρ+p≥0, so w≥−1 always — it reproduces the sign of the DESI DR2 evolving-dark-energy signal with no new fields, and a direct BAO+CMB fit (validated against ΛCDM at χ²/dof=0.99) places it at the ΛCDM level (Δχ²=+0.44), unable to reach the phantom crossing its null-energy bound forbids. GCFT is ΛCDM-equivalent where it mimics ΛCDM and under pressure where it makes a distinctive, testable prediction. All verdicts are falsifiable; none is a formal exclusion. The source is model/toy-derived.