Yeah, that's where I got this quote from. Was there anything written that contradicts this quote or did I misunderstand it? (serious question, as I have read the books in german)
You got it right about Yennefer and other sorceress advisors manipulating royal marriages and such. As for Ciri getting married to the prince of Kovir, Ciri goes there herself at the end to find out what it is they want with her, and she agrees to do it. But circumstances change quickly in Rivia when she goes to say goodbye to Geralt.