I wouldn't say "maximum overdraft charge", because it implies there is such a thing as an overdraft range...from minimum to maximum.

The whole concept of "massimo scoperto" doesn't exist in US banking...either you have gone below 0 (or below your extended credit line/overdraft protection limit) and therefore your check/debit isn't honored and you pay a fee, or you don't. In Italy, it is much more flexible, you can go below 0, the debit is honored, and the fee is a percentage of how much you went under, and for how long...so in the end, I would say "overdraft commission fee".