https://docs.kde.org/trunk5/en/extragear-utils/kdesrc-build/conf-options-table.html#conf-cmake-options The error seems in following phrase: "Use this option to specify what flags to pass to CMake when creating the build system for the module. When this is used as a global option, it is applied to all modules that this script builds. When used as a module option, it is added to the end of the global options. This allows you to specify common CMake options in the global section." Probably should be: "When this is used as a module option, it is applied to all modules that this script builds. When used as a global option, it is added to the end of the global options."
kdesrc-build docs are maintained by its developers.
On a second look, seems the phrasing was OK. Sorry for the noise.