I reviewed the schematic vs the pin mapping page, everything is in sync.
Some signal names are brought out to floating headers, with the schematic showing more clearly that TX3/RX3 are D14/D15 on the COMMUNICATION header, while the notes in Red on the mapping page are not so clear, and the mapping table Not showing them on physical pins 64/63 but instead has physical pins 14/15 (PH2/3) seeming to indicate they are TX3/RX3. So the Red Notes and the table could use a little cleanup.
They do agree (almost - pin 14/PH2 should be blank) that there are 16 pins available to be mapped.