Summary of cINN performance of synthetic spectra as a function of S/N. Expanding upon Fig. 4, shown is a detailed breakdown of the mean residual ${\overline{\Delta }}_{\text{cINN-GT}}$ and standard deviation σ_cINN–GT of each target parameter, distinguishing the lower third (orange), middle third (dark blue), and upper third (violet) of the respective range in the test data. For comparison, the black line shows the respective results over the full trained parameter range. The black dotted line indicates D_cINN–GT = 0 for reference.