In the recipe that I used for raspberry semi-freddo, one beats the eggs and castor sugar in a heat-proof dish over simmering water until it becomes thick. Are the eggs actually cooked? What is the purpose of beating it while it is being heated?
It is to create a custard or crème anglaise (I assume there is also cream/milk in the recipe).
If you do not beat the eggs, they will become scrambled eggs.
so the proper cooking term is "tempering" the eggs.