You can look it up in the event file - it is in the forum at this place:
http://www.ageod-forum.com/showthread.php?p=42555#post42555
It takes some time, but all events are in here, and their triggers and the effects are also. Search on the event name, you usually can find it that way. The programming "language' isn't to hard to understand.
An other option is to look in the scripts - in the ROP map, look under scripts. The scriptpreparse is the easiest I think. There you find under Zeven:
025084 SelectFaction = $AUS
025085 SelectRegion = $Hannover
025086 StartEvent = evt_nam_CMN_TreatyKlosterZeven|0|2|evt_txt_CMN_TreatyKlosterZeven|Event-img_CMN_TreatyKlosterZeven|$Hannover|NULL
025087
025088 Conditions
025089 MinDate = 1756/01/01
025090 MaxDate = 1765/12/31
025091
025092 EvalRgnOwned = $Hannover
025093
025094 Actions
025095 DescEvent = evt_desc_CMN_TreatyKlosterZeven
025096
025097 ChangeVPCount = 20
025098
025099 SelectFaction = $PRU
025100 SelectSubUnits = FactionTags HAN
025101 AlterCuSubUnit = ApplytoList;Kill;
025102
025103 SelUnqUnit = Cumberland
025104 RemoveCuUnit
025105 GenMsg
025106 GenTextMsg = evt_nam_CMN_TreatyKlosterZeven;2;evt_txt_CMN_TreatyKlosterZeven;Event-img_CMN_TreatyKlosterZeven;NULL
025107
025108 EndEvent
So, if AUS
between dates 01-01-1756
and 31-12-1765
owns Hannover,
the treaty of Kloster Zeven is triggered,
it gets 20 VP
Cumberland is removed
(And maybe all Hannoverian units? With the kill command?)
and a message is displayed.
(I think....someone will correct me if I am wrong
)