Indeed, I don't. But languages can be compared based on features. Even a language that doesn't exist can be described based on what features it needs to have. I'm not an expert in type systems, but there is a huge amount of research in how type systems can be described, what features you need to make a type system safe, etc.

If we compare C and PL/I then obviously the syntax differences between C and PL/I are mostly based on the taste of the language designer. But there are a lot of features in PL/I that simply have no equivalent in the C language. Either because when C was design they no longer needed to be in the language or because the features are move to the standard library.

In particular I/O is something that lots of language have as part of the language and C doesn't. So it is in many ways obvious why C a lot smaller than PL/I without losing any power.

But now we go in the opposite direction. We know what the safety outcome should be. So we can make a list of things that need to be in a 'C with safety', even if we cannot predict what the exact syntax will look like.