I am wondering, where are the events found in the progress_events.sql file from the database processed? Is there some kind of list of possible parameters somewhere?
These are mostly scripts that are run based on various events that happen in game. For example, when you equip a speical ring it might have an event scripted to it ( something like gives faction to orcs ). So in the item_stats table this item is given the event "equip_ring_faction". And inside the progression_events table there is:
"equip_ring_faction", "<evt><faction name="orcs" value="100"/></evt>"
So when you equip the right it does an event with the faction operation to increase it by 100. When you remove the right it does the same event but in reverse. Events can be simple operations like this or complex ones that do calculations and can take parameters.