Why do you feel a need to be able to claim that something is "written in Lua" or "Python" when it's using native libraries? Many games are using a mix of languages these days. There's no shame in it and I didn't imply there is.
People get very confused over this thinking that "Python is very fast at number crunching" because of things like numpy which is written partly in C to achieve that performance.
This is like saying Rust isn’t a real language because it relies on LLVM which is written with C/CPP.
That's entirely different - I'm not talking about the interpreter or compiler. Just the runtime code.