In my experience, the wrong food does increase the symptoms. Multiple times I went on bland diet on advice of my doctor after abdominal cramps due to foods. Stayed on it 6-7 days so the piping can heal. Some residual cramps the first couple of days, but much better at the end.
Isolating WHAT foods trigger it is tricky (and painful). I narrowed my unsafe foods down to raw nuts, breath mints, creamy soups with cheese, pepperoni, and excess starch. Fried foods are risky. Once I cut those out of my diet the cramps were fewer and farther between. Unfortunately no two crohns patients have the same list of unsafe foods.
Beware of restaurant chains while recovering. Even though I ordered "safe" foods during a recovery, I had a recurrence. I think I may have a reaction to sulfites, which is a preservative used in many foods in restaurant chains.