My current save file has 20 friendship points and 15 lust points with Rylan, which is enough according to the guide. I've also landed on Sithyrya. What are the exact requirements that need to be met for the date event to occur?
I don't know where you are reading that, but the total points are 20 (friendship and desire). There is also a requirement to have landed in Sithyrya for the first time. That's all.