For the love of order
Studying the books in the library in the Magnificent Mansion, the party learns these things. If you have specific questions, you may also be able to answer them by searching the library.
Guiltspur was built by Karzoug as an arcane research center. The structure was magically reinforced and secured against outside influences. Access to the plane of dreams (Dal Quor) was much easier from here than almost anywhere else.
Karzoug was a powerful wizard who was influential in this area before the eruption.
The room with the juggernaut is a trophy room from a long-term war against serpentfolk.
The large pillar with stairs around it is part of the the Tower of Dreams, which is mostly on Dal Quor. The butterfly with an eye on its wings is a symbol of Desna, associated with her power over dreams. This particular symbolism seems to have either fallen out of common use, or to not be present on the characters’ Material Plane.
Numerous dissections were performed in the room with the four fluid-filled cylinders. There is a large amount of information about the anatomy of many creatures and how it functions. There is one text that seems to cover permanent, magical alterations of the body. It is an advanced text, and assumes a level of knowledge that no one in the party has. Even the vocabulary used has terms that the party is not familiar with.