Cucur jagung feels like a safe snack because there is corn in it. The corn is fine. The problem is that a fritter is a sponge, and deep frying is how you get oil into a sponge. Roughly 7g of oil ends up in each piece, which is 60 calories on its own, so the fritter is about half oil by calories before you count the batter.
The real damage is the format. These are sold hot in a bag by the half dozen for a couple of ringgit. You buy a bag on the way home, you eat them in the car, and 720 calories are gone before you have parked. That is not a snack, that is dinner. If you ate a proper meal and then had the bag, you are 700 calories over for the day and you will not have registered eating anything.
Numbers here are estimates against a normal 40g hawker piece. Some stalls make them small and thin, some make them the size of your palm and soak them properly. A big greasy one is closer to 180 than 120, so use your eyes.