Andrewmoreton:
Sight is not magicable,
He says with way too much conviction for a highly debated topic.
Andrewmoreton:
the limit seems pretty much to be sight of the eagles and that is worthless from the moon. Telescopes capable of resolving anything at that distance are centuries and changes in the world view away.
Eyes of the Eagle is a metaphor. It's not MuCo(An). It takes species from over there and brings them to you. Weakening it slightly from canon wouldn't be so bad but it you have a teleport at that level then being close is usually good enough.
Andrewmoreton:
Not all the world will be empty but from the viewpoint of Medieval Europe Asia and India are exotic and far away places full of monsters. You could go with the historical version but that is a huge amount of research and inventing whole new systems of magic and of course deciding how their different world views collide with the Ars Magica medieval europe construct a task worthy of a mjor publication of multiple books.
As America and Australia are unknown I would jsut ignore them, and are knowledge of them is limited. If you are sensitive to the possinility of offending people you are going to have to tread on eggshells as what I have seen of central american cultures inclines me to believing them to be infernally dominated in the ars magica context. The settled culture of North America largely died of plague before anything was recorded about them so that's another minefield. Again to do something accurate would be a great work of scholarship.
It's mostly that whatever is there. Be it normal geography or 3 other versions of eurasia and africa. Players would immediately look down and see them and wonder what is there.
Andrewmoreton:
Me I would go with you can only get to places which I am ready for you to got to. I would hate to develop China and have them go to India. As being on the moon is already beyond hermetic limits I would jsut impose flaws on whatever their breakthrough is and control it that way. Access only by the Faerie or Magical realm works, no teleportation there.
I see no reason anyone would need a break through to get to and stay on the moon. It defines the lunar sphere it's not beyond it.
Changing that interpretation would be a possibility. But it makes things a lot harder logistically.
Andrewmoreton:
Also IIRC teleportation is largely not teleportation as modern thinking goes but rapid motion between two points which smacks you into the Lunar sphere so if you don't want it justifying its failure is easy.
Teleportation works sort of however your table agrees it does.
By A&A it is like going in and changing the XYZ position coordinate of the target to something else. How that resolves is mostly flavor.