If the industry had a consensus about what constitutes a well designed language, there would be far fewer languages than what we have now.
Every new language coming into existence is being designed by people who are not satisfied with any of the existing options, and decided to make their own.
The designers of Go-lang think it's well designed, but many others disagree.
Some disagree because they think lacking generics is bad.
Others disagree because they think a GC is slow and communicating via channels is slow.
The designers or Rust think it's well designed because safety is of the utmost importance.
Others disagree because they think Rust has high friction.
Some language designers want to prioritize "enabling good developers to get work done", while others prioritize "preventing average/mediocre programmers from making errors".
Some people think a well designed language has compile time type checking, others think dynamic typing is better.
Now, when it comes to my personal opinions, here they are:
The official compiler should be really fast. It should be able to compile a large code base in under 1 second.
It should be able to cross-compile to other platforms with minimum effort.
Compile time type checking is absolutely essential.
It should be able to effortlessly compile the project to a single statically-linked native binary executable.
It should enable a mode of programming where the programmer has control over memory (writing custom allocators, running without a GC, etc), while still providing ways to help the programmer to just write code without having to worry about these things when needed (e.g. optional GC or ARC).