Since the slaves of Meereen do not speak the common tongue (as evidenced by their encounter with Grey Worm), there is no reason for them to daub the "Kill the Masters" slogan in English (which stands in for the common tongue).
When Brienne and Jaime are saying their farewells, the camera pans out to reveal Jaime wearing his sword on his left side. For accurate efficiency of unsheathing a sword, it should be worn on his right side, since he now uses his left hand for sword fighting.