We assess dataset agreement and late-time predictive adequacy in $\mathrm{\Lambda }$ cold dark matter ($\mathrm{\Lambda }\mathrm{CDM}$) and its sign-switching extension, ${\mathrm{\Lambda }}_{\mathrm{s}}\mathrm{CDM}$, using a suite of Gaussian and exact non-Gaussian consistency diagnostics. Both models are constrained with cosmic microwave background (CMB) measurements from Planck, Atacama Cosmology Telescope, and South Pole Telescope, baryon acoustic oscillation (BAO) data from Dark Energy Spectroscopic Instrument Data Release 2, and low-redshift Type Ia supernova data from Pantheon Plus + SH0ES. We find that commonly used Gaussian tension metrics can significantly overstate inconsistencies when broad, non-Gaussian posteriors are combined with tightly constrained datasets. In contrast, the exact non-Gaussian parameter shift indicates excellent consistency between the full CMB and BAO observations in both models. The ${\mathrm{\Lambda }}_{\mathrm{s}}\mathrm{CDM}$ extension modestly improves geometric compatibility at intermediate redshifts, although reductions in parameter-level tension do not necessarily imply improved predictive consistency. These results highlight the importance of exact, non-Gaussian, and predictive diagnostics for robust assessments of cosmological model consistency.

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• Cosmological parameters
• Dark energy