Reading through the GitHub repo, I see Rust, Cyclone, and Pony as idea sources, but I was surprised to not see Ada (https://en.wikipedia.org/wiki/Ada_(programming_language)) or SPARK (https://en.wikipedia.org/wiki/SPARK_(programming_language)). Both Ada and SPARK are mature, production-ready languages that have strong safety guarantees and concurrency built-in.

SPARK in particular might be worth looking at for another idea source depending on Project Verona's goals and needs.