This card does a couple things that are inobvious.
1: It makes repeat testing to beat a hard challenge more consistent. You know that moment when you've just got to try a test, and your odds are low but plausible? You might commit a card like Overpower or Perception but that'd only get you up to a net +1 over the difficulty. This version of Unexpected Courage can do precisely this, it does'nt guarantee the success on the first action, but it'll come back and give you another go, so that hard you're gunning is'nt "so hard that it's not worth trying", it's "Successful eventually".
To give you a precise case: a Wendy Adams trying to get the last clue from a 4-shroud like the Cellar. Ye's it might fail the first time, but it's certainly worth trying for.
2: Pump numbers for "Fail to succeed" events, the likes of "Look what I found!". Sometimes you'll encounter a hard spot, like Cellar, and a Wendy Adams attempting to pick up clues from there might struggle to even play "Look what I found!", especially on Hard difficulty with very big penalties in the bag. Unexpected Courage pumps the numbers, so you'll either succeed or drastically improve your "Look what I found!" chances. And it'll come back too!