first of all: I'm german, so please excuse my rather incorrect english...
There are a lot of possible events for the HRE as they were reforming a lot during the centuries. I'M posting just three of them by now but if you [PI

] or anyone else is interested in the history of german and the empire's law I can add maybe 20 or more events.

(I'm studying german law and therefore the history of the law of the HRE)
Title: Prosecutor of the Empire ["Reichsfiskal"]
Description: The emperor is weak! To uphold his laws and rights it's preferable to hand over the controlling of these to a prosecutor.
Trigger: It has to be at least 1421, you have to be emperor of the HRE.
Button: Choose between having a prosecutor and not having one.
Effect: -heir +stability -revolt risk +tax -prestige -relations to the electors of the HRE
Information: In the year 1421 the Empire created a new civil service post for the emperor to prevent his laws being broken or his rights being disobeyed. Unfortunately this was understood as an impairmant though the emperor didn't seem to be capable of maintaining his own administration.
Title: Taxation for the Empire ["Reichssteuer"]
Description: The emperor is in need of money to maintain the structures of the Holy Roman Empire!
Trigger: It has to be at least 1471, you have to be emperor of the HRE
Button: Choose between enabling taxation and not.
Effect: +stability cost modifier +revolt risk +tax +all members of the HRE get a modifier transferring a small part of their income to the emperor
Information: In the year 1471 the Empire introduced both a wartax and a civil tax aiming to maintain the structures and preventing opposing nation from declaring war on the HRE.
Title: Freedom and Peace for the Empire ["Ewiger Landfriede"]
Description: All members of the HRE will have to swear the emperor eternal peace. If they do, they can't declare war on the emperor anymore.
Trigger: It has to be at least 1495, you have to be emperor of the HRE
Button: Choose between enabling enacting or not.
Effect: +stability (emperor) +revolt risk (members) +all members of the HRE get a modifier removing the possibility of declaring war on the emperor.
Information: In the year 1495 there was the Diet to Worms reforming the HRE. There are more events based on the Diet possible like
- superior Court of Justic ["Reichskammergericht"]
- order of executing ["Reichsexekutionsordnung"]
- a new taxation system ["Gemeiner Pfennig"]