China's system of temple numbers, era names, and nicknames is indeed very complicated. However, both the temple name and the title were added by later generations after the emperor's death, and only the era name was owned during the emperor's reign. As for the historical ones called "Wuzong", it seems that there are only three, Tang Wuzong (Li Yan), Yuan Wuzong (Haishan), and Ming Wuzong (Zhu Houyi). I will mainly explain the temple number, the name of the temple and the year number, to give you a general understanding and reference.
Temple Number: The temple number originated from the Shang Dynasty, and after the death of the ancient monarch, it was enshrined in the zongmiao temple. In fact, the establishment of temple numbers is relatively strict, and not every emperor has a temple number. For example, the Western Han Dynasty had 12 emperors and 7 temple numbers, and after the Guangwu Emperor Liu Xiu took the throne, he cancelled three more. Only Liu Bang, Emperor Wen of Han, Liu Heng, Emperor Liu Che of Han, and Emperor Xuan of Han had temple names, and the other three (Emperor Yuan of Han, Emperor Cheng of Han, and Emperor Ping of Han were revoked).
Nickname: After the death of the ancient emperor, posterity gave him a pertinent title according to his deeds and virtues. According to the Yi Zhou Shu Tan Fa Xie: "Jing Wei Tiandi, Moral Knowledge, Kindness and Love for the People Yue Wen; Wei Wei Enemy Virtue, Ke Ding Disaster, Qu Zhi Duo Poor Wu; Rong Yi Gongmei, Zhao De Youlao, Shengwen Zhou Da Yue Zhao..." From the title of an emperor, we can see the merits and deeds of this emperor before his death. After Qin Shi Huang unified the Six Kingdoms, he abolished both temple and temple titles. After Liu Bang, the ancestor of Han Gao, succeeded to the throne, he restored the system of posthumous titles. In ancient times, every emperor who inherited the unification had a nickname, such as Han Gaozu Liu Bang, "Han Gao zu" is Sima Qian's title in the "Records of History", in fact, the correct name is called "Han Taizu", Liu Bang's temple number is "Taizu", the title is "Gao Emperor", because his merit is the highest, so the title is "Gao Emperor".
For example, Emperor Liu Che of the Han Dynasty, after his death, the temple name was called "Sejong", and the nickname was "Emperor Xiaowu", because the Han Dynasty emphasized filial piety to rule the world, and after the emperor's death, except for Liu Bang, other emperors added a "filial piety" in front of the title. For example, Emperor Xiaowen, Emperor Xiaoxuan, Emperor Xiaoyuan, etc., all have a filial piety character. Before the Tang Dynasty, the title was originally a word, but after the Tang Dynasty, the title was a long list, such as Tang Taizong Li Shimin's nickname "Emperor Wenwu Dasheng Daguangxiao". Song Taizu Zhao Kuangyin's nickname "Qiyun Li Ji Ying Wu Rui Wen Shen De Sheng Gong to Ming Daxiao Emperor", Ming Taizu Zhu Yuanzhang's nickname "Kai Tian Xing Dao Zhao Ji Li Great Saint Zhi Shen Ren Wen Yi Wu Junde Successful High Emperor" is almost longer than generation, so the emperors after the Tang Dynasty only called the temple number, not the title of the emperor.
Year number: The year number is a name used by the Chinese feudal dynasty to chronicle the year! The era number system was created by Emperor Wu of Han, and before Emperor Wu of Han, there was no era name. Emperor Wudi's first era name was "Jianyuan", but the change of era name during the reign of Emperor Wudi of Han was very ordinary, and he used 11 era names during his reign. Ancient emperors generally had to change their era names when they encountered major events and important events such as "heavenly descent" or internal and external troubles. Since the beginning of the Ming Dynasty, the emperor has only one era name, so the emperor of the Ming Dynasty, because the name is too long, the emperor calls both the temple number and the year number. For example, "Kangxi, Yongzheng, Qianlong, Jiaqing" all belong to the era name of the Qing Emperor, and the Qing Emperor only has one era name, so when calling the Qing Emperor, they all call the year number, not the temple number. At present, Japan is still using this chronology method, and their era names were introduced from the Tang Dynasty, that is, after the "Dahua Reform".