All five nations have treasures which is bein guided by the ruler of the nation. Only that person, meaning the current ruler is aware about it.
In some cases, It can be known to a few members of the family or people close to the ruler.
After the unification of Memoria, it was left to the nation representatives whether to disclose to Melania , the empress.
It was only known now that the treasures were stones and only their locations were known to Melania and her then council members,
Neither the properties of the stones nor the mechanism on how to nullify the effects of the traps set in the room where the treasure was kept was known.
The actual key was given and passed on to the next to be leaders or the now nation representatives of each kingdom.
One such example is
Insaria-
The transportation crystals is such a type of treasure. It is known by every citizen as it is not the actual treasure but the derivative of the stone.
The imperial family had the exclusive rights of this stone which was given to Melania then taken back after her death.
As the agreement stated that only a member of imperial family could handle or use the stone or the empress of Memoria.
Member of the imperial family can include the blood relatives or someone working for the family and is loyal and sole person who is elected to take such a responsibility.