One thing to remember is that there is a natural cap to rolls of 40, as that is the max that can be rolled on the dice.
Also remember that the 14+ is actually a total roll or 33 or higher usually. Is the table perfect? Nope, but it is a starting point, and a possible option that could be included or used.
and the Nat20 critical success could just easy be knocked out, or subdued, completely disabled, etc... as desired.