Ideas and suggestions.

In short: that's exactly how it was intended. The goal is not to make the skill good, but to increase its usefulness from practically zero to situational.

Docent Picolan, increase the first level of Estates to 400. So that this situational usefulness exists even on Jebus Cross. Over 7 days (average game length), that would be 2800 — enough for one hero. It would make it viable to start with a hero who has Estates or not to dismiss a bought hero with Estates. More expensive bidding would become possible. There would be more variety right from the start. Meaningful variety, not just situational!

Currently, 350 — yes, it's more than before, but imo it's too little. That's 2450 gold over 7 days. It doesn't really motivate playing such a strategy. No one will level Estates to level 3 on Jebus Cross anyway. On larger maps, a +50 gold increase at level 1 also won't make much of a difference.