The completeness of stellar spectral libraries in all stellar evolutionary phases, parameter space (effective temperature, surface gravity, global metallicity) and chemical abundances, is required to build more sophisticated stellar population synthesis models to decode the enclosed information of galaxies of varying types. On the hand, due to distinct nucleosynthesis sites, the comparison between magnesium and calcium can provide relevant information to understand the evolution of asymptotic giant branch (AGB) stars, the IMF (production of Mg/Ca in core-collapse supernovae varies with the mass of the progenitor), or the SFH. In this context, I use the X-shooter Spectral Library (XSL) as a benchmark to train developed stellar population models and include alpha and carbon-enhancements in them. The XSL, with a moderately high resolution (R ~ 10000) and a large wavelength coverage (300-2480 nm), represent a huge improvement over previous empirical stellar spectral libraries. For that purpose, we employ the automated abundance estimation procedure GAUGUIN for deriving high-precision, accurate magnesium and calcium abundances from a wide variety of stars well distributed in the Hertzsprung-Russell (HR) diagram. The resulting abundances follows the abundance pattern of the Galaxy, reproducing a plateau in the metal-poor regime followed by a decreasing trend even at supersolar metallicities, as also predicted by Galactic chemical evolution models. 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 and metal-poor metallicity regimes and massive galaxies with enhanced [α/Fe] in the high-metallicity regime, with an unprecedented precision. On the other hand, the determination of carbon abundances will be used to study the discrepancies between the observed and predicted CO bands, studying the origin of the chemical abundances in globular clusters, and the contribution of AGB stars to the total light in the infrared, with large implications in the stellar masses and ages of high redshift galaxies. First results points to promising carbon abundance estimates for a wide variety of stellar types. In conclusion, this will significantly contribute to the quality of research of external galaxies' abundances in the near future, with a special focus placed on current and next-generation of field spectrographs such as MEGARA, WEAVE, 4MOST, or JWST's NIRSpec.