Nonogram was easy, but I've solved a few hundred or thousand nonogram puzzles in my life, so I wouldn't be able to tell you how that'd be for someone who's never played any. It's the only one of the puzzles where a bunch of people might need to go read the rules before understanding what's going on, which may not be ideal. Sudoku, by comparison, is harder, but you can summarise the rules in like 1 sentence (4x4 Sudoku is not too difficult).
I solved Defuse based on the "code" only, while having no idea what the letters refer to. In hindsight, that's fairly obvious. It's probably fine, but I can also see people having a lot of trouble with it if they aren't great at puzzles.
For the crossword, I'm not great at word puzzles, especially not on a timer. I'm especially bad at thinking of words with 3 adjacent consonants. I tried like 3 letters and then ran out of ideas, so just tried all letters, and the very last letter was the correct one.