Ratio of the CO-to-H₂ column density $N_{\text{CO}}/N_{{\text{H}}_2}$ versus $N_{{\text{H}}_2}$ for the post-processed galaxy, compared with observations of (optically) diffuse (Rachford et al. 2002; Crenny & Federman 2004; Sheffer et al. 2008) and dark (Federman et al. 1990) molecular clouds in the MW. The black, green, and blue points are from the galaxy post-processed with HYACINTH but using different CRIRs (as indicated in the legend). In each case, the points are selected to have a gas-metallicity Z ∈ [0.7, 1.3] and χ ∈ [0.35, 1.3] to match the respective values in the observed data. The column densities are calculated in a position-position-velocity cube of 156pcl56pc× 5 km s⁻¹, to match the velocity dispersion in the absorption measurements.