Appreciate the feedback! I thought about adding a hint mode (something like "this box is almost complete") but didn't have time to implement it for the jam.
If you correctly label the box, it will mark the input field as green and lock it.
Another idea I didn't explore was doing something like Chants of Sennar: having a list of all clues and allowing you to assign a label to a clue and lock it if you are right.