This is confusing, but maybe just poor paraphrasing. It should really just say that it can be used anywhere that Lua is used. The rest of the article describes Jank as "garbage collected" and "not a systems programming language", which obviously makes it so you can't run it anywhere C++ is used.

A bit disappointing, because I was looking forward to a more system-y Lisp-y language from that description.

From C++ to Clojure: Jank language promises best of both (259 points, 3 months ago, 103 comments) https://news.ycombinator.com/item?id=42871743

I quit my job to work on my programming language (58 points, 3 months ago, 32 comments) https://news.ycombinator.com/item?id=42658898

Jank development update – Moving to LLVM IR (190 points, 6 months ago, 49 comments) https://news.ycombinator.com/item?id=41845669