To further increase the accuracy of the predicted reaction barriers, the 571 configurations were re-labelled at the ωB97X-D3BJ/def2-TZVP level of theory, which have been shown to better describe non-covalent interactions and activation energies in organic systems. This re-labelled dataset was then used to train the final ACE MLIP. Further details on the training method are provided in SI §S4.1.