I don’t think this is true. When you visit a tag page it is possible to silent that tag in the notification bell.
One specific problem are posts that apply to more than one country in the same language domain, but not all of them. With country tags it should be pretty easy to handle that.
In general, I’m concerned about the fragmentation of communities. I think starting right away with country categories we would be putting barriers between communities and trying to solve problems we don’t have yet. If that separation makes sense after we started the language category we can always create new country categories later and migrate content there.