I don't have any experience with Jsonnet, but from what I can gather, it appears to be a Turing-complete functional programming language. Leporello.js, on the other hand, is a UX concept that can be applied to any functional programming language, including Jsonnet.

In fact, I believe it's possible to write code in TypeScript that would be very similar to Jsonnet. TypeScript provides the capability to create compiler plugins, which can restrict the allowed language subset, effectively making it more limited and suitable for configuration