Structural Convergence Between the Concentric Orbital Cosmological Model and Vortex Field Theory: Emergent Metric, Effective Cosmological Constant, and the J < 1/4 Boundary

I identify and analyse five points of structural convergence between the Concentric Orbital Cosmological Model (COCM) and Vortex Field Theory (VFT), two independently developed frameworks linked by a local constitutive equivalence at a matching radius r*. The convergences concern: (i) the induced metric as the constitutive object underlying the equivalence; (ii) the conditional inheritance of nonlinear diffeomorphism invariance by the COCM effective sector; (iii) the emergence of an effective cosmological constant from vacuum structure; (iv) the analogy between the nontrivial branch conditions in both theories; and (v) the correspondence between the COCM boundary J<1/4 and the VFT curvature-control regime. These results are conditional on the hypotheses of both programmes and do not imply that one theory is derived from the other.