Comparison between the CNN-emulated photon spectra and the corresponding numerical-model spectra on the fixed Fermi/GBM energy grids. The left and right columns show the NaI and BGO bands, respectively, for three representative epochs (t = 1.0,  3.0,  and 5.0 s; colors). The upper panels present N(E) as a function of the energy, while the lower panels show the logarithmic residuals (in dex) between the emulator prediction and the numerical reference. Solid curves and open circles denote the numerical-model spectra and the CNN-emulated photon spectra, respectively.