Due to a mistake in "Table 5-16: IEEE 1588v2 Egress Transmit Signals" of the Altera® Low Latency Ethernet 10G MAC User Guide (PDF) the tx_path_delay_10g_data and tx_path_delay_1g_data signal descriptions refer to a data width of 16/22 for the Arria® V and Stratix® V devices.
tx_path_delay_10g_data tx_path_delay_1g_data signal signals should refer to a data width of 15/21.
This problem will be fixed in a future version of the Low Latency Ethernet 10G MAC User Guide (PDF).