

Prison Break.
Season one is breaking out of prison. So far so good.
Season two is a manhunt. That’s fair, it’s the aftermath.
Season three is breaking out of prison… again! But this time in Panama. Technically that is the show, so alright.
Season four is a secret shadow organization who can cure all diseases but don’t.
Also there is a post-show film that adds another prison break for some reason. Also I’m learning the show was revived for a fifth season, I can’t say what that’s about.
In this example it was an attack roll, and a critical hit as a result of the halfling luck trait, so it played out perfectly.
In the case where it were a skill check, you are correct that there are no crits for skill checks. However rolling a natural 20 is a rare event and as a DM you could choose to reward it. Conversely hitting delicate machines with a battle-axe is usually a mistake.
The machine working at half capacity is a reasonable reward and consequence.