2250 EGR cooler bellows leaking

[NDISX15]

How important is this issue since the truck is demandated aside from yes there's soot tracking on the block now so obvious exhaust leak under the hood?

My concern is possibly pulling some cool/cold air in to the valves/cylinders possibly.....but would that be possible?

For reference, the leak is at the accordion looking part of the egr cooler towards the front of the block.....I dont have a picture of it on me