Having flown an Airbus 310 before, this phenomenon of downwind brake temp going up was observed quite significantly.
The answer in my opinion is simply the control wheel or aileron deflection inputted by the pilot in landing roll. Assume a left cross wind, manual landing with automatic braking, the usual pilot tendency is to apply aileron into the wind (mostly overdo it) thereby inducing more a/c weight on the left set of wheels. Obviously this is an aerodynamic increase of weight on left set of wheels with same Hyd pressure on both sides. How much the airplane decelerates and how drifting is controlled by brake modulation is beyond the scope of this discussion. The left set of wheels have higher resistance to ground and hence temp rises faster.
Assume the same landing with an autopilot and from what I have observed the autopilot might use side slip/crab etc method but the input on landing roll really never showed a difference in brake temp on any side later on as much as in a manual landing.
To sum it up - more aileron on landing roll more difference on BRK temp.