Here's some example code that will accomplish what you would like. The idea is that we create an array of elements based off the OBX-5 field split by \.br\. We remove the existing OBX segment from the message, then re-add OBX segments back in with the individual items from the original OBX segment, this time each in their own segment.
var obxString = message.getNode('OBX-5');
var obxArray = StringUtils.splitByWholeSeparator(obxString, '\\.br\\');
message.removeAllNodes('OBX');
for (var i = 0; i < obxArray.length; i++) {
if (StringUtils.length(obxArray[i]) > 0) {
message.addChild('/', 'OBX', 'OBX|1|ST|Coding Summary^Coding Summary||' + obxArray[i].trim());
}
}