I recently had the same issue. A player heard a specific name and rolled knowledge check to find anything they might know about the significant NPC. It was in the 30's as well. I told them something very superficial, but that would connect directly to other things in the module. It also gave them a bit of indirect insight into the nature of things to come. Without spoiling much here, I told the player that the NPC was related to the First World and the name was thousands of years old. Due to the long span of time most information has been lost. However, this gives them hints at fey (first world) great powers (thousands of years old). As the module progresses they continue to find first world references and further information from parties more directly aligned with the first world (fey creatures in the area).
The knowledge netted them an initial framework. The remainder of the module painted the picture of this NPC on that initial framework. However, the knowledge check did not give them any significant information, because their character simply could not know that information.