In many Taiwanese novels I encounter the word 姊姊 (older sister). This is of course one of the first words a Chinese learner will encounter. My question is more regarding the reading of it. On the mainland you are most likely to encounter the spelling 姐姐, which is read jiějie in both China and Taiwan. According to the Cross-Straits Dictionary, 姊姊 on the other hand, should be read as jiějie in Taiwan and zǐzǐ in China. If a person from say, Beijing, were to read a Taiwanese novel, would he read 姊姊 as jiějie or zǐzǐ?
If the word was 垃圾, we would most likely get lājī from a northerner, and lèsè from a Taiwanese. But that is the case of "same characters, different pronunciations". Here it's not the reading that's different (both would call older sister jiějie), but rather the characters. I'm less certain a northerner would actually say zǐzǐ.