I struggled with the Process [/tmp/embedded-pg/PG-XYZ/bin/initdb, ...] failed over the last week and figured out a solution that I can't find documented anywhere. I wanted to post here to save others some time!

My unit tests were passing locally, but failing during CICD in Docker container using AlmaLinux:9. None of the suggestions in the Readme resolved my issue. I was using a non-root user, the temporary directory had correct permissions, and there was no issue with the binaries.

Upon lots of investigating, I found that the flavor of AlmaLinux:9 I was pulling was not defaulting to the correct locales. It looks like this is resolved in some flavors of AlmaLinux:9.5

Adding glibc-langpack-en to my system installs completely resolved my issue.
RUN dnf install -y glibc-langpack-en

You may also need to use .setLocaleConfig() when building your EmbeddedPostgres instance