That presumes that we knew it would have been such a problem when CMake was started (back in the late 90's; I started contributing in 2010). The issue is that a lot of semantics are tied up in the way the language works between the list representation, variable lookup, scoping, policies, etc.
I once contributed to and even built a number of projects using CMake, but have since vowed that I'll never EVER open another CMakeLists.txt again, and will toss any CMake-based project that has builder errors I'd otherwise have to debug. CMake is the only build system of the dozens I've used over the last 30 years that has driven me to this. For awhile I held up hope with the advent of "Modern CMake", but alas it's not enough to fix things, and I doubt the syntax could ever be fixed.
The alternative is to keep smearing more and more lipstick on the pig and hope people don't keep abandoning it, which is a shame because CMake COULD be great.