Hi! I would like to point out as I have pointed out in comments above, that Beast and CMake (though might look similar) are different tools. Beast is an actual build system, that looks at your beast file and carries out the tasks you have specified. It runs at the very base level executing whatever you tell it to.

CMake and Meson on the other hand are Meta build systems. They do not run any build commands on their own. They use other build systems like Make, Ninja to carry out everything. Think of them as a fancy wrapper around build systems. Beast is here as an alternative to Make and Ninja.