How to "see" complete error message in Notification Centre - macro failed

Not really.

According to OS X El Capitan: Use Notification Center, you should be able to:

See missed notifications
In Notification Center, click Notifications, then do any of the following.

Get details: Click a notification to see the item in the associated app. For example, click a Mail notification to see the email in Mail. When you open an item, it’s removed from Notifications view.

But that is NOT happening for Keyboard Maestro notifications:

For example, when I click on this notification from the Notification Center dropdown list:

it does nothing. The full notification is NOT shown.

@peternlewis, is there anything we can do, or you can change, to allow us to show the full notification after the initial display has disappeared?

OTOH, Growl does an excellent job. I don't know how I did this, but somehow I have set KM to use Growl for error notifications. Example:

I find Growl much more user friendly than the Apple Notification Center.