So my entire Austria campaign i was trying to take control of the HRE. I would wipe out the "holy roman empire" faction, take frankfurt, lose the election, then automatically lose frankfurt, then repeat. I must have taken Frankfurt 5x from various factions. It felt unrealistic, but okay, i guess i have to wipe out every other german faction that calls themselves the HRE then ill be the de facto HRE.

Eventually the holy roman empire screen no longer pops up when clicked So I took over 18 regions and I am unable to name myself as the Austrian Empire, because it says i am still part of the HRE. The HRE doesn't exist and there is no option to leave it. I might be wrong but it seems like the HRE mechanics just don't work in its current state if you are playing as a minor faction.