High-pressure metal polyhydrides or superhydrides are the best conventional superconductors known, exhibiting zero resistance close to room temperature, however typically only at Mbar pressure conditions. In principle, due to the electron-phonon coupling mechanism of superconductivity, their electronic and superconducting properties can be determined from first-principles calculations, which has led to a large library of predicted compounds that combine energetic stability with high-temperature superconductivity. Experimental synthesis efforts have followed suit, but in many systems discrepancies arise between measured phases and what ground-state calculations predict. Differences in composition or structure then almost inevitably lead to very different electronic properties. Here, based on a series of collaborative efforts with experimental partners, I will discuss some of the underlying challenges for modelling and how experimental findings can be reconciled with more advanced simulations.