Also supports is kind of relative,
"CHR is very new and experimental feature of the engine, it is based on wildly unsafe functionality which could result in memory corruption, subtle bugs, etc."
I also think that doc page is a little old. The feature is over 2 years old now and hot reloading is inherently "unsafe" in any compiled language. It's just letting you know that Rust's safety guarantees might go out the window if there are bugs in the code that handles hot-reloading.
Also that was only one example, there are other similar ones.
You can do very easily do quick and dirty in C++. (And shoot your foot off also..but that's a different thing)
Such code is of course crappy, but the OP wants to test if things are fun before committing to implementing them properly. Rust wants things done properly on the first try (which usually is a good thing, except throw-away prototypes).
That approach gives you the best of both worlds: high-performance core with high-velocity iterations for gameplay. Don't use Rust or C++ for scripting... madness lies that way.