Create a simple program to launch a FileChooser dialog, then run the program in different languages. On Windows and Linux, the dialog shows localized messages for the buttons "Open", "Save", "Cancel" ... , but on Mac, the UI are always in English.
Attached the image for FileChooser dialog opened by Safari and JavaFX on Mac. The system language is German, the left side dialog is from Safari, it's localized, while the right side dialog is from JavaFX, it is in English.
This happens only on Mac.