There's nothing "more direct" - the different APIs for different languages call into the same underlying library, and most of them are more accessible and easier to work with than C++.

Z3 is presumably written in C++ for performance, but without data I am very confident the vast majority of programs that use Z3 consume it via one of the other APIs.

I personally like to avoid the “writing in C++” experience. :/

The author might not know C++ and you don't need to use C++ to effectively use z3.