Short reply.
Answer lies on the fuel/oil heat exchangern which heats the fuel before it enters the FCU and cools the oil.
In our instance,the leak occurred forward/upstream of the heat exchanger which then was doused with a very cold stream of vapourised kerosene .The opil temp dropped to a negative value,which led the crew (apparently) to discard the info.
The oil viscosity is dependant on its temperature.high viscosity brings high pressure...
With hindsight,the two indications Low oil temp + high oil press were very coherent...
These alerts were the first to appear as the imbalance would be shown after quite an amount of fuel was lost.