DERG The engine will have demonstrated max oil temps etc during endurance testing prior to certification. Cooling will also have been demonstrated to the Regulator's satisfaction.
Are you suggesting that RR have changed the values subsequent to certification?
But before comparing with other engine manufacturers you need to be sure that the temperature is measured at the same place so as to compare apples with apples.
The RB211 535E4 has a max oil temp of 177 deg C, the 524is 100 deg C. But 535 is measured at scavenge return, 524 at outlet from oil pressure pump ie after cooling.
So I am not surprised that oil technology etc has moved on since the 535 so as to be able to cope with a very modest temperature increase.
Oil temperature is specified on the Engine Type Certificate Data Sheets which are easily available online. Well, the CAA ones are, EASA not so easy. FAA probably easy.