We found that the melting point of CsLiF 2 is much higher than that predicted by CAL-PHAD model, as Fig. shows. Models predict a melting point of CsLiF 2 of ⇠ 370 C, while experiments show it melts at ⇠ 443 C. This is a big di↵erence, suggesting that interaction parameters need to be updated in the model. In CALPHAD, the equilibria of ternary, quaternary, and higher-order system are usually extrapolated with the use of binary and ternary experimental data. The discrepancy in the melting points should be valuable for validation of new ternary and quaternary interaction parameters in LiF-KF-NaF-CsF systems. Note that the discrepancy could be related to the di↵erence in coordination numbers between binary salts and FLiNaK-CsF discussed above.