It's been stated that the FADECs have nothing to do with the rudder. That is true for the 787, but it's not always true. The 777 will automatically apply rudder to correct for an engine failure, but only if it knows the engine has failed. It relies on the data coming from the FADEC. That might be the cause of the confusion.
The 787 will do the same but it does not rely on data from the FADEC. It uses the IRS to detect the yaw. In fact, it will correct for anything that causes uncommanded yaw, not just engine failure.