During a recent safety recall, when changing a bar between the clutch pedal and master cylinder a substantial spillage of brake fluid (and later leakage due to not re-assembling properly) soaked into the sound deadening foam in the engine compartment.

This has been dripping off the bottom of a cross member underneath the car for more than two weeks now. The car is presently back at the dealership for the forth time to sort this problem, where they say they have "rinsed off" the spilled/leaked brake fluid.

What damage may have done or might be done in the future and what reassurances should I seek before accepting the car back?