This is a really great idea, specially if you can write a transpiler from general C++ into modified C++ (it can error out on corner cases and ask for manual intervention, but trivial stuff like adding missing braces can and should be done by an automatic tool, like rustfix is used to migrate between Rust editions https://github.com/rust-lang/rustfix)

But here you didn't tackle the main thing: a plan to make simple business logic not corrupt memory and cause havok with UB! Dereferencing arbitrary pointers is a dangerous operation that shouldn't be done in everyday code. If I'm writing data structures I'm willing to think about UB, but if I'm choosing the color of a widget I'm less so. I'm not expecting you solve this hard problem, but at least a general direction or a half solution that works for a % of the cases would be cool (or at least state this is a long term goal).

And of course there's the comparison to Rust, but Rust is actually just a data point in this solution space and perhaps new languages can afford to try new approaches