Hi Old School - I can't see a single thing wrong in what you're doing with the names. I strongly suspect it's a bug! Having said that, all I've ever done with this facility is ensure the name/characteristics of the starting king, and haven't really tried to set up a long list of famous ones. There is one other observation that may be pertinent - I very often find that my second king acquires the first king's characteristics on ascending the throne.

Let's say Henry I (good attacker) begets Prince Henry (nothing special), then dies -- Henry II is now a good attacker. Unfortunately, I don't have the vaguest recollection of which campaigns in which version/mod of the game this has occured in, so can't check the relevant heroes file. It MAY be an instance of the "famous kings" working correctly. I've never really noticed any OTHER king having any stats other than those he had as a Prince (which suggests none were "famous"), only this one transition from starting king to first heir.

It may be of no help, but maybe it adds an unsuspected piece to the jigsaw...