A comparison of reference DFT (+F vib ) and CE data are shown for all three models in Fig. . Their rootmean square errors (RMSE) from 10-fold cross-validation are 2.5, 3.7 and 4.1 meV per formula unit, respectively. While the RMSE is generally low, we note that there are some outliers especially when vibrational free energy is included, which is to be expected from the observed differences between DFT and MLFF vibrational free en-ergies. To some degree we expect that the CE can act as a noise filter due to the large amount of data present-at least in the absence of systematic errors. Generally, we observe that the mixed phases are significantly stabilised due to vibrational free energy.