> You either place faith on a build step working deterministically when it was not designed to work like that

I'm sorry, what? Why would a build not work deterministically?

> If you decide to put faith on your ability to run deterministic builds with a potentially non-deterministic system

If your build is non-deterministic, how can you have any faith in the binaries it produces? You would have much larger problems in that case.

> You use git to track changes, regardless of where they came from

You probably don't want to do that if it is 70% of your codebase and slows down all your developer's git.

> Then you need to have internationalization test steps for each localization running as part of your integration tests to verify if your build worked

I'm convinced you've never used a build system before. Your build should fail if required files are missing. Downloading translation files at build time from some artefact repository vs storing them in git is how a lot of companies do it.