If CMake can't find the qmake executable, it is a problem with your environment's PATH setting. The failure to build your conversions is an irrelevant side effect. If CMake can't find an executable, it won't be able to build whatever it is the executable is supposed to build.

CMake doesn't have God-like powers to find executables out in the universe (or even on your PC) unless you tell it where to look. That's done either with your system PATH, CMake variables, or a combination of them. Setting the PATH or a CMake variable isn't a "workaround", it's how the thing works. Look at cmake-gui.