Requiring castles to train Grenadiers further emphasizes the message that the unit has unqiue mechanics, as well as the fact that gunpowder was not used until the Jurchens had to defend their land after the conquest.
I used to share my own Khitan concept too. But I think that if the current Khitanguts could be split, the new Khitans would still inherit some current design, like the Blacksmith bonus in my concept would be replaced with the bonus of double Forging line effects in the current design, as well as the Knight line would be removed.
That being said, the devs rarely reference the concepts from the community to a great extent.
They like to copy ideas from the community for potential civ A to new civ B rather than maintaining the original intention of the ideas.