From TactWiki

Each continent on Telon has a quest available that allows you to acquire a document from the ruler of that continent that is needed in order to build a guild hall. These quests require large amounts of Information, as well as other diplomacy items.

Here are the quests for each continent:

Thestran Commission for Guild Halls
Qalian Guarantee for Guild Halls
Kojani Sanction for Guild Halls

All links have images of the (small) guild halls located under the Quest Completion section.

The image below provides a quick glance reference to the types of information needed for the respective hall writs and the parleys which are the means by which to attain the information.