Best-fitting models retrieved for the three objects. The spectra correspond to the three detectors of a single order of CRIRES⁺. This wavelength range contains several ¹²CO and ¹³CO lines. The observed data are shown in black, and the corresponding best-fit models are in blue (J1200), green (TWA 28), and red (J0856). Residuals are shown in the bottom panel. The average scaled uncertainty is indicated on the right side of each panel. The data and the models are displayed in the rest frame of each object. The full wavelength coverage used in the retrievals is shown in Appendix D.