The correct location for script batch.ini is in the radicore <root> directory.
The version of errorHandlerBatch() in the RADICORE download already contains the correct five arguments. The version which you are using must be incorrect.
The file config.local.inc is entirely optional so it is not an error if it is not there. If it exists it is used instead of config.inc.
The error reported at includes/language_detection.inc on line 279 is wrong as that line does not try to convert FALSE to array. On my system the command is:
$_SESSION['user_language_array'] = get_user_languages($_SERVER["HTTP_ACCEPT_LANGUAGE"]);
The error reported at /includes/include.session.inc line 993 is wrong as that command does not contain a call to 'strtoupper()'. On my system the command is:
trigger_error($GLOBALS['php_errormsg'], E_USER_ERROR);
In case the variable $GLOBALS['php_errormsg'] is empty I have amended the code to use a default value. See the attached file.