One possible approach is certainly to choose a
"representative" country
per language, and define freeness as only free in
that country
specifically. So en.wiki's ambition is to be free only for Americans.
Perhaps es.wiki's goal will be to be free for Spaniards, and/or
Argentinians. de.wiki will be focused on freeness for Germans. etc. I think
that would be... suboptimal, though.
I agree that it would be suboptimal - most of the English speaking world
would be at a disadvantage then! You would also have to ask difficult
questions about Anglo Saxon, or Portuguese, where the language to country
link is not as clear.