In a couple of dynasties, ranking titles vary from each one and I don’t know what this manga is based off of, but in general, going off of what most chinese traditional dramas are like, Yu er would be higher with his Madame Consort rank. The princess consort will remain with her title since it’s a harem and it seems her brother who we haven’t been introduced to yet has incredible authority since seme had to ask him for permission to put on the title of Madame Consort to MC. She’ll definitely remain until she does something crossing the line for when nobody can defend her no longer, even her brother.

So, Yu-er gonna have the title "Madame" after just being a concubine. The Princess is she gonna still be the Princess or she gonna sent back to her family?
So, Yu-er gonna hold the highest tittle in the palace or still the princess?