I've seen it work the opposite way in tactical. A unit will be on fire with 1hp, you win the battle only to find out your unit is gone.

The real question for this is whether a fire resurrected unit was still on fire by the end of the autocombat. I've seen a mechanical unit die and continue to have a flame for several turns after. It might be tracking the units even after death based on the flame. Need more info to confirm

In the Kin Slayers burning-resurrection case, the fire ended when it was killed by fire, IIRC, and then it resurrected.

I was able to reproduce it with a hell hound vs a pikeman. The weirdest part is when I was trying to get a screen capture of the pikeman attacking post-flame-death, the autocombat replayed differently depending on when I paused it. Sometimes the flame damage would show up and other times it wouldn't. The autocombat replay isn't consistent in these cases.

thats a great work!

although I refrain from reading it, to not spoil myself fun from playing AoW1.

In case you didn't know, you can enable debug mode in the registry (HKEY_CURRENT_USER\Software\Triumph Studios\Age of Wonders) by adding a DWORD value "Debug Mode" to the "General" key and setting it to 1.

It mainly gives infos on selected hexes and tactical combat, but maybe it can offer additional insights regarding some of these bugs.

If you swap items between two heroes during tactical combat, by having one hero drop an item and the other pick it up; and if the two heroes are not on the same hex in strategic, after the combat you'll have an empty bag of items on the battle hex.
If you then save and reload, the game will crash with some exceptions.

If a razed city which was previous upgraded is rebuilt, it will lose its upgrades, but sometimes still be able to make the higher tier units. I can't see why this is sometimes the case and other times not.

Does this include walled cities (and watch towers)? Will a single goblin bomber capture a city that has walls but not defenders (or watch towers)?

Yep, and he doesn't even explode to do it. A bomber is as good as a ram in capturing unoccupied, walled structures.

Bombers occupy an odd space in auto-combat. In non-walled auto-combat, they are an attacking unit that explodes to do damage. In walled auto-combat, my experience is that they explode to do damage to the walls, but they retreat if the walls have already been destroyed by the time they get their turn in combat, instead of then attacking the enemy units. There may be situations where they act different; I don't know.