AnotherGame is a mod for ToE 3.1.

Is this feature borrowed from Heroes of Might and Magic VI?

The question is, has a way been found to change the amount of healing from the tent?

Maybe you also have sieges banned? This is a very strange restriction; I've never heard of significantly strengthening a Castle being considered overpowered.

Yeah. They saw how Revenge deals damage starting around turn 3-4, when it’s already endgame on the map, and starts dealing more damage than regular units, so they complained about it being overpowered. But the fact that you can only win an equal battle with Revenge (if you make it to the endgame with decent forces), while Meteorite can win any battle, for some reason isn't taken into account. Well, whatever, that's what people think.

Well, that's great. Because replacing Invisibility with Retaliation would be one thing, but +4 to Initiative is a bit too much.

I don't know what stage of the game you play at, but this looks like overkill. The Capitol costs 10,000 and gives +2,000 gold per day. Even a very unprofitable warehouse costs only 5,000 and 5 stone.
In my opinion, upgrading mines should have their price lowered to 1000-2000 (except for the Gold mine). I hope the upgrade is not repeatable?