Minor bug fixes

src/Entity/EventInstance.php

@@ -340,6 +340,10 @@ class EventInstance extends EditorialContentEntityBase implements EventInterface
         'label' => 'above',
         'type' => 'string',
         'weight' => -4,
+        'settings' => [
+          'date_format' => 'F jS, Y h:iA',
+          'separator' => '-',
+        ],
       ])
       ->setDisplayOptions('form', [
         'type' => 'daterange_default',

src/EventCreationService.php

@@ -530,7 +530,7 @@ class EventCreationService {
 
     // Create a message to indicate how many instances were changed.
     $this->messenger->addMessage($this->translation->translate('A total of %items event instances were created as part of this event series.', [
-      '@items' => count($event_instances),
+      '%items' => count($event_instances),
     ]));
     $event->set('event_instances', $event_instances);
   }