European nobility's coronation ceremonies are quite similar, and they are basically held in churches, especially the ducal ceremonies, where the main rites are held inside the church.
This is mainly because, traditionally, dukes, like the kings of various countries, are considered to be granted their rights directly by the gods, rather than deriving them from the kings, and thus their ceremonies naturally have more religious elements.
However, this isn't good news for Leonard Ethan, as he is unable to enter the church and therefore can't see the most important parts of the ceremony.
Even the parts that Leonard can see are testament to the importance of this ceremony, such as the fact that the clergyman at the ceremony is the Chairman of the French Bishop's Council and the highest-ranking clergyman in the Catholic Church of France.