I tried a couple of quick tests and couldn’t make it work as-is. I made a change to the ko-calendar.js that seems to work but it might have other side effects.
The change is to put a <pre>
block around the title text.
Replace this line
entryTitle.appendChild(document.createTextNode(titleString));
With these
var preTitle = document.createElement('pre');
preTitle.appendChild(document.createTextNode(titleString));
entryTitle.appendChild(preTitle);
Then you can add a \n in the Event Title Format, like this…
[STARTTIME] - [ENDTIME]\n[TITLE]
The side effect is that this will inherit any <pre></pre>
style that the rest of your page has, which might not be what you want. I will keep it on the list for future updates, but it will need more work.