On the map “School of Sword and Magic (3.2)”. Auto-translated

Please explain a couple of points regarding the game mechanics: 1. On the "Sword and Magic School" map (3.2), the Grail is listed among the available artifacts in the text file, but heroes do not have the "dig" function. How can I make it so that they can dig on this map? 2. On the same map, I noticed that not all heroes from the standard list are available for hire in the tavern (I have an additional mod installed that adds campaign heroes to the hiring list). For example, Axel, who was the starting hero for Haven, did not appear in the list of heroes available for hire after I defeated him. The same goes for Anwen; she simply did not appear among the heroes, even when I intentionally cycled through all the heroes available in the tavern (hiring and firing them). Is there a limit to the heroes that can be hired, and if the number of hero slots on the map is less than the number of available heroes, are some heroes simply excluded by the game when the map is generated, and do they not appear in the tavern at all? Or is there something else going on? 3. Is it possible to add artifacts from campaigns to the list of artifacts generated on maps of this type, for example, "Wings of the Angel" from the Necropolis campaign?

On the "School of Swords and Magic" map (3.2), in the text file, among the available artifacts, there is the Holy Grail, but heroes do not have the "dig" function. How can I make them able to dig on this map?

If I understand correctly, the Holy Grail is allowed, but it is not buried. That is, there is actually nothing to dig up... So bury it, and you will be happy.

Is it possible to add artifacts from campaigns to the list of artifacts generated on the map for this type of map, for example, "Wings of the Angel" from the Necropolis campaign?

I'm not sure, but I think these are ordinary relics, so they should be generated.