Bayesian log-evidence normalized to the highest evidence model, $ln{\mathcal{Z}/\mathcal{Z}}_{\max }$, as a function of FG flexibility N_FG (squares in the left panel), ${\overline{T}}_{21}$ at z = 17 (middle), and calibration amplitude A_cal (right, defined as $A_{\mathrm{cal}}\equiv \sqrt{a_0^2+a_1^2}$). Models with N_FG ≥ 9 are omitted in the middle and right panel for visibility, as they overlap with N_FG = 8, 9. Models below the horizontal gray dashed line are decisively disfavored ($ln{\mathcal{Z}/\mathcal{Z}}_{\max }\le -4.6$). We use red and blue colors to represent scenarios of no T_cal and with T_cal , respectively. The error bars in the middle and right panels represent 95% C.I. regions around the mean. In the middle panel, the region below the standard expectation (${\overline{T}}_{21}<-210$ mK) is shaded in gray, while the vertical black dashed line indicates ${\overline{T}}_{21}=0$. In the left panel, the blue and red crosses show the maximum log-likelihood ratio, $ln(\widehat{\mathcal{L}}/{\widehat{\mathcal{L}}}_{\star })$, normalized to our highest evidence model.