Drilling into brick through stucco
Well drilling stucco may fracture it and allow leaks but you have a brick wall behind this so that rule is not quite the same as stucco over wood frame. When I have to drill or cut stucco I use concrete bits at a fairly high speed not a hammer drill hammer drills break it up and catch the mesh making a bigger problem. The higher speed makes a lot of dust and usually easily cuts wire mesh (not expanded metal mesh) once you have your holes fill them with silicone sealer then put your screws in the pressure pushes the sealer into the cracks, if I see any cracks I will use a grout sealer above and around the hole.
For stucco with expanded metal do not drill it will have very bad results. I usually use a masonry blade and cut a hole normally for a box, but the masonry blade will cut the stucco and will cut the metal but the metal will Accelerate blade wear have a few extras. Grinding a cut line works best but cracks can radiate from the cut. Again a grout sealer liberally applied helps to seal cracks if the cracks are large fill with paintable silicone sealer and make sure to texture the surface nothing looks worse than a smooth line when a coat of paint is used to cover and final seal. In both cases. I really have not had problems with high speed and wire but expanded metal the drill bit will grab and pull you in creating huge fractures 1/4” wide up to a foot away, with cutting in a box I move from side to side to keep from over heating  and had the best luck with that and the thinnest masonry blade I can find I have used angle grinder and a skill saw more control with a skill saw but normally for a larger box. Those are my tips hope they help.