One small thing we should fix while we're in here:

Events aren't required to have a description. If they don't have one we'll render an empty "description" header with no description. This is the existing behavior, but is confusing/inconsistent/undesirable.

It would be better not to render this section at all if the event doesn't have a description. You can do this with:

$description = $event->getDescription();
if (strlen($description)) {
  // Render the description, then addTextContent(...)
}

So, events with a description should work just like they do with this patch, but events with no description should just not render the section at all.

Great -- one minor tweak and we're good to go.