My nephew sent Truffle Gouda & Herve Mons Gabietou along with some Genoa Salami and bread via USPS overnight mail on Weds, 12/23. However, it did not arrive until today, 12/26. Would the cheese still be okay to eat?
If the cheese is packaged in a vacuum wrapper, it should be OK, certainly the gouda. This method of packaging allows gouda style cheeses to be transported without cooling even in summer.
I am not familiar with the other cheese but would myself be willing to eat or serve it.
Cheese was made, in summer when the cows gave plenty of milk, to preserve that milk to later in the year. A few days in winter transport should not hurt it.
US food safety standards may not be met during transport but in winter hot temperatures are very unlikely.