Well, technically are all the players "nordgens" - but now this term equals with fast trainer being sold by Nordeus directly. I have several power trained fast trainers and if I decided to sell them, they still remain fast trainers even for the new manager.

But there are several clubs named by the managers to look like Nordeus generated (in order to boost the demand) so the only "reliable" hint is, imo, the value of the player in relation to his age and quality.