
This might not be the best explaination but I think it's just a ritual. In many places Kings and emperor's did day, weekly, month, or yearly rituals. Some where for the civilians or workers to see the king and get tasks others are for their gods. Regardless of it was a coronation I am sure their would have been someone that seemed to take the lead more. Normally the person crowned isn't necessary in the centry untill once it ends but it seems like he is the most important the whole time. That and this ritual only has his lecturing and with a water bowl so I think it's just a regular ritual they have to do every so often. The time line is confusing thought but I think after 16 ended it's back to their current time.
i'm a bit confused about the timeline. ch. 17 is the coronation of the dude right? before lok heun went to the lair of demon, he didn't assassinate the emperor yet? if that was the case. if he was in hiding why was it in the beginning chapters people knew he was royalty