I would argue this confirms what the OP said cmake is really not very friendly to the user (not developer). Reading through the cmake sources for options is equivalent to "read the source".
But you only have to do this if you don't want to run an actual GUI or ncurses UI which does this for you for some reason ? What would you suggest instead ?
(and if your meta-build system does not allow to do that, I'm sorry but I'll have to build a meta-meta-build-system on top of it which implements it and no one will like it)