At one time I just gave up on using any config formats and instead went back to the good old simple "use the programming language as the config file too" approa

At one time I just gave up on using any config formats and instead went back to the good old simple "use the programming language as the config file too" approach. It's certainly not cross language capable but when your editor knows exactly what's there and what's not with auto completion from the config file, that was a superior experience than caring about cross language issues that may not even be a problem depending on the project. If you must, you can easily make an identical copy of the config in the build process to convert it to another language.