You can review the supported language scripts ([lang]_run.sh) at
https://github.com/jcrodriguez-dis/moodle-mod_vpl/tree/v3.3.8/jail/default_scripts
These scripts check, compile or prepare the source code to be run. Their aim is to generate the programs/script named vpl_execution or vpl_wexection that really will be run.
Notice that to customize an activity you must go to "advanced features"> "execution files" and write your own vpl_run.sh script, the system will use your vpl_run.sh for your activity instead of any [lang]_run.sh applicable. To easily replicating customization you may go to "execution option" and use the "based on" feature ".
Best regards,
Juan Carlos.