> It’s not really a problem, you just adjust the size of your assumed storm.
Adjusting how you call the storm doesn't make the wall bigger: that's the problem. (It also makes their statement untrue in the present day, regardless of if it was true when the wall was designed.)
It's the engineer defining his design criteria (the 'design-storm'), based-on and benchmarked-to local historical data, including recurrent intervals.
The wall doesn't need to be bigger if next years data changes. It was designed for a (this year) 100yr- or 500yr-storm, not a guess of hypothetical future one.
Adjusting how you call the storm doesn't make the wall bigger: that's the problem. (It also makes their statement untrue in the present day, regardless of if it was true when the wall was designed.)