Dagger founder here. We moved away from CUE because the number one complaint from our early users was having to learn CUE. The number two complaint was bugs in the language that we diligently escalated upstream, but would never get fixed, including crippling memory leaks.

We shipped multi-language support because we had no choice. It was a major engineering effort that we hadn't originally planned for, but it was painfully obvious that remaining a CUE-only platform was suicide.