I'm hoping they translate Baron Tamago to "Egg Baron" or else the jokes with his transformation won't make sense.
I'm pretty sure they're going to stick with Tamago, like it is in the manga and the subs. But then again, I was sure they would use "Conqueror's Haki" but we ended up with "Conqueror's Spirit".
As for the jokes, they would still be pretty apparent. No one needs to be familiar with Japanese to put 2 and 2 together that Hiyoko might mean "chick" and Niwatori might mean "chicken".