As I understand it, using the standard quest editor, you need to create a separate quest for each artifact. Therefore, I implemented it using a script (I am currently checking if Valeria has all three artifacts, but I can make it so that any hero only needs to collect them). As a result, I made the following changes:
1) Fixed the quest for finding artifacts
2) Removed these three artifacts from generation (so they cannot be bought in a shop or found in a utopia)
3) Disabled astral gates (so there is a reason to look for keys)
4) Made it so that enemy heroes cannot take these artifacts