I'm translating a subset of statically typed Python to C++:
I use very much a "pidgin" subset of the language -- one that is easy to step through in the debugger! The problem with all these fancy new features is that you're more likely to trip over bugs in the debugger, e.g. incorrect line number information and stack traces.
So the generated code doesn't even use operator overloading, which e.g. C++ 11 range for loops require. I want to be able to see everything. Yet I also want to use features like templates, virtual methods, and strict enums, which C doesn't have.
Another "modern" project that does this is the Souffle datalog compiler, which generates "monolithic" C++ programs with heavy use of C++ templates:
(I heard about it due to its role in prototyping Rust's type system)
C++ templates are not fun to write but they have some interesting properties for code generation.
So I would happy if we stopped writing C++ by hand. But I do not like the alternative rewriting inferior versions of existing programs/libraries in entirely new languages. They often have new bugs, are slower, and have fewer features.
I really like what Zig is doing to reuse existing code (i.e. bundling a C compiler). I think that both Rust and Go ecosystems have led to a lot of fragmentation and redundant efforts.
The "History of Clojure" paper has a nice view on that. Why Clojure is tied to the JVM. So it's part of the ecosystem rather than fragmenting it.