"Jerusalem" is spelled the same way in Hebrew and Aramaic (if you ignore the vowels); but in Hebrew it's pronounced "Yerushalayim", and in Aramaic it's pronounced "Yerushleim" (as it appears in the Akdamut.)
The text of the Ketubah is primarily Aramaic; so when reading a Ketubah in Jerusalem, do you pronounce the city's name the Hebrew way (as we're used to) or the Aramaic way? And why?