Hmm - I know Limsa Lominsa still welcomes beastmen traders. I think Ul'dah used to (and now emphatically does not; beastmen currently aren't allowed within the city at all).
Trade is a big motivator for learning language. Obviously Limsa still does - look anywhere in the lower decks and you'll probably see at least one beastman. And I think Ul'dah accepting beastman trade is within living memory - I remember this one leve in Drybone where you have to escort a clueless Amalj'aa (eta: see below) merchant away from the settlement, and he doesn't understand why they won't trade with him ( :( ).
And as for the Sylphs, they seem to have something of a diplomatic history with Gridania that could explain why they would learn "Common" as well.
Trade is a big motivator for learning language. Obviously Limsa still does - look anywhere in the lower decks and you'll probably see at least one beastman. And I think Ul'dah accepting beastman trade is within living memory - I remember this one leve in Drybone where you have to escort a clueless Amalj'aa (eta: see below) merchant away from the settlement, and he doesn't understand why they won't trade with him ( :( ).
And as for the Sylphs, they seem to have something of a diplomatic history with Gridania that could explain why they would learn "Common" as well.