How can I capture scores when using other libraries?

I am creating a custom content type which wraps several quiz-based content types. When I use the quiz-based content types on their own the scores are recorded correctly as I see a 'results' tab in my Drupal 7 site and the scores are listed there. However, when I wrap these libraries into a new library the scores are not recorded and the 'results' tab only shows data for 'Name' and 'Start time' but 'Finish time', 'Points awarded' and 'Max points awarded' are blank.

I tried going back to basics and tested the greeting-card-with-task.h5p which is available through the using other libraries tutorial. The issue persists for this content type, with the two wrapped libraries (multiple choice and fill in the blanks) not recording finish time, points awarded and max points awarded when used within the Greetings Card library, but recording scores with no problems when used on their own.

Does anyone have any suggestions for how I might go about getting the greeting-card-with-task.h5p to record the scores correctly?  

I should add that I am able to access the xAPI event from the parent library, by appending the code below to the bottom of greetingcard.js. I'm thinking that within this function I need to write the code that will store the result. Any ideas how I should proceed?

H5P.externalDispatcher.on('xAPI', function(event) {
if (event.data.statement.verb.display['en-US'] == 'answered') {
console.log('I need to store the score');
console.log(event);
}
});