According to someone on Novelupdates who looked up the webnovel reviews, the story seems to be very well-received by Korean readers.
https://forum.novelupdates.com/threads/the-crown-princess-audition.109363/page-2
Turns out the main focus is more on political intrigue/survival and has little romance.
Prince is going to become a human sacrifice once he turns 20. Magic weakens once a while, and the nobles are the only one who can use magic. The nobles will sacrifice a chosen one during this period (ex. the prince) and split up the sacrifice's power among themselves.
the plot is a bit dumb.. why go along with something you know that there's something wrong??? its like am reading mystic messenger..... dumb protagonist thats been keeping swept away with the flow 😦
it's obvious that the one who instigated the search was the one that stole it (probably anyway). anyways it's nice to see that the two (sisters?) have gotten closer.