Indeed, the Normandie was a suicide spot during the Cultural Revolution and because of that the building got nicknamed the diving board: this is supported by many accounts, including testimony from my neighbors. But at the time of writing I was unable to find any specific names, so I relied on a source that claimed Shangguan Yunzhu was one of those suicide jumpers. In fact, a more authoritative source – the memoir written by her daughter – points at a different location of her suicide: an apartment house at the crossing of Gao'an Road and West Jianguo Road, where the actress lived at the time.
While you cannot erase the internet, I hope no more articles quoting my poor research and attaching Shangguan Yunzhu's suicide to the Wukang Mansion (aka The Normandie, aka 武康大楼) emerges in the future.