Problem simulating transceiver megacore Nativelink

You bet. I have another example where I simply write to a 16-bit fifo a state machine then reads that fifo and write it to the transceiver block. When the Transceiver block receives data I have a state machine to save the received data to a 16-bit fifo and also set a flag indicating data has been received. A nice simple interface that anyone can use, simply write to a tx fifo, set a big high to transmit the data, and on the receive site, monitor a receive interrupt indicating data has arrived.