Is “Yan Yan's performance in the Battle of Hanzhong.” true?

The novel describes Yan Yan partnering with Huang Zhong during the Battle of Hanzhong, participating in the attack on Mount Tiandang, and personally killing Wei general Xiahou De (Chapter 70 of Romance of the Three Kingdoms: "He happened to meet the old general Yan Yan, who raised his blade and cut Xiahou De off his horse."). In official history, after Yan Yan was released by Zhang Fei at Jiangzhou, there are no further records of his life; he did not participate in the Battle of Hanzhong (Records of the Three Kingdoms, Book of Shu, Biographies of Guan, Zhang, Ma, Huang, and Zhao: "Fei, admiring his valor, released him and made him a guest. Wherever Fei went, he conquered, and he met with the Lord in Chengdu.").