The comparison between the chemical shifts predicted by the KRR model and the experimental resonances is shown in Fig. . In this figure, the KRR predictions for individual T-sites were assigned to the experimental ones using an almost constant correction (≈ 1 ppm) that accounts for a systematic offset which may stem, for example, from the approximation used for conversion from chemical shielding to chemical shift (see Section 2.4), or from inaccuracies of the reference DFT level, exploration of which are beyond the scope of this contribution. The current assignment of the experimental Al shifts to aluminium located in specific T-sites differs from previous T-site assignments. This discrepancy is to be expected, as prior cal-culations of chemical shifts typically relied on either Lippmaa's approximation or the single-structure approach (see Sections 3.1 and 3.2 for reference), and thus we expect our assignments to more closely represent the realistic conditions of the NMR experiment.