We already have language lawyers for implementing compilers. I think the right solution is to take away most of the "convenience" features. Most people don't touch all of them anyway because they don't know how they would interact. But everyone joining a team would have to learn them.

Why do so many computer languages experience scope creep? Including C++ and JS.

Sort of. I mean that you have to write specifications gor programs in English so precise and literal that it's like writing legal contracts. Compiler writers don't do that except in language specs. They use codd. Closest thing, which would be used in addition to English, is using a mathematical notation like Z or TLA+ for anything ambiguous. That's standard in high-assurance development.