In Settlers 6, there are a few game mechanics that are useless or simply for decoration, as extra content. All theories should be posted in the comments.
List of mysteries Edit
The gem maker's hut is a building that is only shown in the Harbor in Settlers 6: Eastern Realm. It has no workers and a Builder builds the building and upgrades it.
Royal City of Vestholm Edit
The Royal City of Vestholm is a city previously owned by the King and Queen, but was taken over again. In the period where it was taken over, in Mission 15: Vestholm, it appears to have gained many new territories.
There are many small villages from different climates in separate corners of the city.
Village of Eastholm Edit
There appears to be a village called Eastholm if you explore the map in both variations of Vestholm. In Mission 15, the village is hostile and delivers a knight in a prison cart to the harbor. However, in Mission 1, it is a Undecided faction. In the village, it has a barracks with mercenaries from the temperate climate.
Why is it so aggressive to the player's faction?
Goods to trade with the bandits Edit
In Mission 15, the bandits show that they can trade stone and wood in the diplomacy menu.
Why even implement that if the best status with them is "undecided"?