Is it safe to eat opened liverwurst after the expiration date?

Yes in the US the most common date seen is not the so called expiration date it is a sell by date. There is no expiration date required on US foods, except for infant formula. The USDA has no idea how you plan to store your food. Some food can last for years if stored properly.

So think of it like this, could you think of a reason why a store would sell food that is going to expire the same day they sell it.

For instance milk is typically good for 7 days after the SELL by date if kept cool.