AnotherGame is a mod for ToE 3.1.

I don't know how you play, but in a normal game, situations often arise where you encounter enemy dwellings starting from week 2-3. And converted dwellings are clearly more useful than developed mines, especially at higher levels.

In the late game, isn't the weekly increase of certain native creatures (let's say, a Fortress) needed to "control" some 5000 (although I was talking about a fair price for a dwelling, corresponding to its level)?

Well, even choose the most suitable standard map ;) Dwellings are usually placed between mines of common and rare resources. High-level dwellings are further away. That's the first thing.
Secondly, if all players have an equal opportunity to convert, where is the balance broken? (a balance break is when 2 Elves and one Magician, for example, when one Elf takes a dwelling from another Elf and transports it to his own castle over huge distances (also a plus in favor of conversion) ).
The only thing that can be done is to make it so that when capturing a dwelling, a non-removable guard accumulates in it over time.