i'm pretty sure they had uncooked beef.
it doesn't take long to go from raw to medium rare. ask them to get you medium rare beef, if that's what you want! if you do, and the gaucho points to something on the skewer that's too well done, say, "no, i want it much redder than that" or "that's cooked too much." they hear this all the time and they are prepared to answer the call... they aim to please.
presumably, you were in the restaurant for at least an hour. they easily could have brought you whatever you preferred. it is, after all, the operating principle behind a churrascaria. i've had really bad experiences at some moderno locations, but it was never because food was unavailable. they were usually lapses in service. there has always been more meat than anyone should be allowed to consume, available in what ever temperature one desired.
let them know what you'd like.
you are truly the captain of your fate and the master of your soul.
also, for the record, they're probably not using charcoal at moderno.