Lattner is best known for starting the whole LLVM project. Swift is just a small side project in comparison, it just got adopted by Apple for some reason.

LLVM is one of the most influential pieces of software of the past decade. Hero worship isn't good but credit where credit is due.

You're confusing language development with autonomous vehicle development. Think of the long term goal. It's desirable to move fast and fix things with language development in the near term, to achieve a more perfect design and accelerate its maturation at the temporary cost of more volatility. After this process achieves a high level of maturity, said design principles may offer a safer, more reliable programming system that would be better suited to safety-critical applications.

Additionally I'm sure we can all agree there is no substitute for maturation through time and usage in the field. Which frankly is an argument for more popular languages over obscure ones. None of the ones you mentioned are ready for safety-critical system development (including Swift 3), but which one is most likely to achieve widespread adoption and field testing in the long run?