It's not just language, it's how connected the social graph is. The centre of gravity for each country is within that country. If you want something to spread w

It's not just language, it's how connected the social graph is. The centre of gravity for each country is within that country. If you want something to spread with virality, you need to start fires in each country separately; and even then it may end up with the stigma of being "that X thing" where X is some other country. Booking.com did it very well, but of course the audience for that is intrinsically mobile and cross-border.