14 and 15 are both Technology based and the Orb is their friend
1,2,3,4,5,12,13 are Caskets histories and whatnot
8,9 are Urns biological Data
6,7,10.11 are Tablets language and whatnot.
Nice and concisely put.
I might be imagining it, but there might be a clue there in the object names.
Caskets - reliquaries and such used for storing historical items of import.
Urns - used for storing biological remains.
Tablets - both the historical and modern kind, used for reading/writing.
Orbs - Erm, yeah someone might need to help me with the analogy here...