The completeness of stellar spectral libraries across all evolutionary phases, parameter space and chemical abundances, is essential to build more sophisticated stellar population synthesis models to decode information from galaxy spectra. On the one hand, due to distinct nucleosynthesis channels, the comparison between magnesium and calcium can provide relevant information to understand the evolution of asymptotic giant branch (AGB) stars, the IMF (the relative production of Mg versus Ca in core-collapse supernovae varies with the mass of the progenitor), or the SFH (Star Formation History). On the other hand, determining carbon abundances helps assess the contribution of AGB stars to the total infrared luminosity, with significant implications for estimating the stellar masses and ages of high-redshift galaxies. In this context, we use the X-shooter Spectral Library (XSL) as a benchmark to train advanced stellar population models, incorporating both alpha and carbon-enhancements. The XSL, with a moderately high resolution (R ∼ 10000) and a large wavelength coverage (300-2480 nm), represents a huge improvement over previous empirical stellar spectral libraries. For this purpose, we employed the automated abundance estimation procedure GAUGUIN to derive precise and accurate magnesium and calcium abundances from a diverse sample of stars well distributed across the Hertzsprung-Russell (HR) diagram. Additionally, preliminary results indicate promising carbon abundance estimates. In conclusion, the provided XSL abundance catalogue (Santos-Peral et al. 2023) is suitable for improving the modelling of evolutionary stellar population models with empirical α-enhancements, and its implementation will allow us to study small galaxies with nearly solar-scaled abundances in the sub-solar, as well as metal-poor metallicity regimes and massive galaxies with enhanced [α/Fe] in the high-metallicity regime, with an unprecedented precision. This will significantly contribute to the quality of research of external galaxies' abundances, with special focus on current and next-generation of field spectrographs such as MEGARA, WEAVE, 4MOST, or TARSIS.