Thanks that was really useful. My revised config is:
(start and end date/time, one of many possible formats)

config: { dateFormat: "llll",

// dateEndFormat: “YYYY-MMDDTHH:mm:ss”,
dateEndFormat: “llll”,
timeFormat: ‘absolute’,
showEnd: true,
urgency: 0,
getRelative: 0,
fetchInterval: 2 * 60000,

calendars: [ {

I found this site a bit easier to follow:
https://devhints.io/moment