MGSP+ II applies the modular variational principle to homogeneous and isotropic FRW cosmology. It introduces a cosmological stiffness scale CmodC_{\text{mod}}Cmod that controls how modular energy responds to FRW deformations, and shows how CmodC_{\text{mod}}Cmod can be extracted from background cosmological data. The paper derives predictions for effective non-Gaussianity, scale dependence and large-scale structure observables originating from modular stiffness and “FRW compression”, providing the first concrete cosmological tests of MGSP+.