Yeah, that makes some sense. I might not even ask for Discern Realities there. Like, in order to Discern they have to do something which includes messing around with the trapped chest. So I might have them just straight engage the trap and ask them to deal with it before it releases on them.
But yeah, you can Reveal an Unwelcome Truth by building on the fiction any time you can make a move. You can also trigger the trap (deal damage) or engage it (tell them consequences or put them in a spot). You have a lot of choices, it's just that Reveal can be a good one for Discern because sometimes it's hard to like Use Resources or Damage when they're just investigating a room. Whatever makes sense situationally, though.
The idea is, at the heart, just making their lives interesting. On a failed Discern, rather than just be like "nope, you find nothing," you can do something more interesting like "oh man, you'll never guess what's really in here..."
That's how I use it, at least.