This is a subject I have discussed at length in the discord. Generally most campaigns apparently don’t encounter a problem because there aren’t typically long periods of peaceful downtime (in the AE campaign I believe the apocalypse happens 3 years after game start unless stopped by PCs).
I don’t think they completely solve the issue but I’ll copy/paste some tips that helped my campaign deal with this with help from Arbrethil and Archon.
1: Calculate personal authority based on income before liturgies/repression expenditure
2: Cap liturgies at an extra 2gp/family
3: Require ruler to spend maintenance equal to his intended rank at personal authority +0 or have neighbouring realms all roll reaction to see if they invade every year
4: “Traditional Society: The ruler is supposed to uphold the traditions of his people. As long as he does not change the tax rate or liturgy rate from its traditional values, he gains a +1 bonus to loyalty rolls with his vassals, who know him to be a rightful ruler. If he changes the tax rate or liturgy rate, it counts as a calamity for the vassals, who make loyalty rolls at -1 per point of change.” (straight from Archon)
5: “Accession: When a ruler takes power, he is allowed to increase Liturgy spending by 2gp in the first month and 1gp in the second month in order to show his appreciation of the people” or whatever.
6: Divine power cannot be used to replicate the entirety of the material component of magical item creation
7: Good random event table (I use one from Harnmaster)
8: Remember that realms are supposed to receive a -1 minor calamity to domain morale on average, usually not PC realms but should be in a long term scenario