untransferable - cannot be given from one hero to another. Translation - it is not transferable.

1) Yes, it is possible even through forbidden artifacts. Princess Aelina (or whatever her name is) also seems to belong to this category. It's approximately the same as creating a boss from a monster. Also, changing rare creatures.

2) The option of checking the artifact on the hero is good. But you will still have to change its description.
For example - Sword of Power = +2 to attack.
In this map: Armageddon's Blade = +10 to attack
If you add a difference of +8 to the hero's attack using a script, it will all work. But the description will still remain, and, if you put on Armageddon's Blade in another map, you will only get +2 to attack instead of the promised 10.

So, in my opinion, the first option is more convenient. We don't lose anything.