That's not what reproducible means in this context. Being able to go from a given release artifact to a git repo is not what the "reproducible builds" project/movement/whatever is about.
Reproducible builds are more about the packaging of something than about specific language ecosystems, so asking about languages that focus on reproducible builds makes less sense than asking about package ecosystems, build systems, and linux distros that do.
Let's look at an example: docker is written in go, and is marked as reproducible in debian, but unreproducible in archlinux: https://ismypackagereproducibleyet.org/?pkg=docker&query=que... (named docker.io on debian https://ismypackagereproducibleyet.org/?pkg=docker.io&query=...)
Why is that?
Well, debian sets the "version.BuildTime" option when it compiles it to a constant value each time it compiles it: https://salsa.debian.org/go-team/packages/docker/-/blob/4f1f...
Archlinux's PKGBUILD doesn't https://github.com/archlinux/svntogit-community/blob/cf04bef...
Because of that, "docker version" on arch linux outputs that it was built on the actual day it was built, whenever that was, and each time it's built that string changes. Hence, not reproducible.
Reproducible builds are about capturing enough information about how something is built, and specific enough build instructions, that two people can produce the same bit-for-bit identical output, and therefore verify that someone didn't compile a malicious backdoored binary, and also increase the chance that each build consistently works or doesn't work, regardless of who compiles it when.