Well I've heard the dicussion on how level gets neglected in BR as far
as the regent and domain rules go. I have a simple solution.

A regent gets a +1 to actions for every ?5 levels he attains?

1-5: +0
6-10: +1
11-15: +2
16-20: +3


He gains +1 to actions of his classes speciality (ie wizards: ley lines,
make/rule sources; thieves: espionage. What LTs of that class do not get
penalties on) every ?3 levels starting at 6th.

1-6: +0
7-9: +1
10-12: +2
13-15: +3
16-18: +4
19-21: +5

What do you think? Simple. Makes sence.

You could even limit it by counting only levels the PC has spent as a
regent (ie. a 6th level Fighter who became a regent at 3rd level would
count as third level for these rules).