Hard-magnetic films with precisely tuned switching fields are of great interest for advanced magnetic microsystems. Here we report on the specific evolution of semi-hard magnetic properties of L10-FePt films integrating a graded concentration of soft cobalt nanomagnets. These nanocomposites are prepared by the combination of MS-LECBD and e-beam evaporation techniques where 8 nm Co nanoparticles are embedded with various x atomic concentration up to 50%, into Fe/Pt multilayers. A subsequent annealing allows us to reach the alloy chemical order for the FePt matrix by conserving Co-rich nanometer-sized inclusions. The focus is put on the interplay between the local microstructure and the coercive magnetic field through a combinatorial approach that involves local determinations of composition, magnetization reversal from scanning magneto-optical Kerr effect and element-specific spin and orbital magnetic moments from X-ray magnetic circular dichroism performed at the Co and Fe Ledges of absorption. We show how the nanostructuration changes the magnetic coercivity, and how both Co and Fe effective magnetic spin moments evolve with the composition of the nanocomposite film.