50 Ohm resistor at SMA connector
Both Baluns are spec'd to have a 50 ohm input impedance, with a 1.5 VSWR (typ), corresponding to a return loss of ~-14.dB.  Assuming the source (the thing driving into J2) is matched to 50 ohms, and the interface from the SMA connector to the balun is 50 ohms, I see no use for the discrete ~50 ohm resistor at the SMA.