CUE is just fascinating to me. I'll bet that we'll see more of it, not less. Agents or not, you don't want everything in a general purpose programming language, especially not what CUE is good at.
I've used both Dhall and Nickel, but haven't tried CUE before.
I do wish that these sorts of languages were more pervasive, as they really are quite useful.
It feels like a lot of tools too eagerly make the jump from pure data (JSON, TOML, XML, etc.) to using a Turing complete language for configuration files (JS, TS, Lua) when something like CUE or Nickel is the ideal middle ground.