So, in my opinion the Feitoria is just a non redeemable concept. It just allows you to hold on longer on maps, and in settings where ressources actually can run out, which then leads to stupid situations, where one player wins, simply because the map makes it hard to push (i.e. Islands). I dont think on any other map the Feitoria is actually ever a viable option.
So I propose a complete rework of the building:
Make it a kind of fortified town center instead. It can produce villagers, and ressources can be dropped of at it.
For the start I propose to keep cost and stats as it is, but remove the required popspace. So the stats for the Feitoria would be the following (In brackets written potential changes, if it proofs to be not useful with the non bracket stats)
So Feitoria as I propose:
Melee armor: 3
Pierce armor: 10
(Building armor: 8, like Krepost)
Create Villagers in 25 seconds (20 seconds)
Has Garrisson space of 20(25) and can shoot when garrissoned (fletching, botkin etc. increase its range)
Every ressource dropped of at the Feitoria is multiplied by 1.1(1.2) instead. So basically this is a 10%(20%) gather rate buff, combined with a 10%(20%) longer lasting ressource buff for any villager that drops of ressources at the feitoria.
(can create the unique unit)
(can research unique technologies)
I think the most likely needed adjustments would either be the cost, or the ressource multiplication factor, but if one of them gets the better version I think the new Feitoria would be pretty useful. It would give you a much easier way to expend safely in the late game, making it very hard to raid that eco, and it gives you an eco bonus, that especially when build on stone or gold gives you back those extra ressources you spent on the building in the long run. Lets say you have the upfront investment of 250g and 250 stone, and you build it on a neutral three tile gold mine, it would give you back at least 240g with the factor 1.1 and 480 gold with the factor 1.2. So it would be an upfront investment, but one that doesnt necessarily decrease the complete gold available to you.
In addition, to this making much more sense from a gameplay perspective, it also makes much more sense historically. Now the Feitoria, becoming a fortified outpost in the colonies of your empire, far away from your homeland, instead of a ressource generating machine that is at the center of your empire, somehow generating profit without any valuable ressources around it.