Treasure Hunt Scenario

Hi, the Treasure Hunt scenario seems to only count unused artifacts, with your number found dropping as soon as they are emplaced on a ship or planet. This isn't the end of the world on ships, though it does feel wacky to scuttle your titan just to get them to count again, but on planets can (and I think has) make the game impossible to complete

 

Unrelated, but in the Defend the Homeworld scenario are the invaders supposed to ignore your frontlines and attack deeper planets almost immediately? I get that it's a smart move from the AI but in the context of the scenario it just feels annoying, at least to me.