Thanks Maciej, glad you enjoyed it! Yeah part of what BuildKit enables is really complex builds, but that has a side effect of generating lots of information that can be difficult to parse through, very much including digging errors out, so completely agree BuildKit needs improvement there.
As of right now, I wouldn't say that CUE specifically has much of an impact; it's sort of like a new "frontend" to BuildKit, but a lot of the output ends up the same.
At Dagger specifically we definitely want to improve this situation. One way we're pursuing that is adding support for viewing the output of Dagger builds in a web interface, which gives us much more flexibility in terms of displaying errors clearly. But this will be an ongoing project, lots of room left.
Does that answer your question?