I don’t fully understand this ask. Kylo doesn’t know anything about Rey. He may have information that he stole from her mind, but that’s basically like saying someone who hacks and stalks you knows everything about you. Its not actually knowing a person, its stealing their info without their consent.
Kylo knows nothing about Rey but what he took from her mind by force and even if it turns out they are or aren’t related, that doesn’t stop the fact that their history from beginning till know is riddled with abuse, lies, pain, and literal torture. Rey can be the daughter of Watto and Dexter Jettster yet it won’t make her suddenly want to hop Kylo’s bones or make Kylo want Rey considering by TLJ, he swears to kill her to hurt Luke…wow….I wonder why Kylo thinks killing this random girl would hurt Luke…
Anyway, compare that to Finn, who may not know how many Beatles Rey ate last Monday for lunch, but he knows who she is as a person, what she cares about and how she treats others. They’ve fought for the other, saved the other, and were ready and willing to die for the other by the end of TFA. Throughout these two films, Finn and Rey’s relationship has been the only thing that seemingly hasn’t been dropped, subverted, or will know need to be readdressed with a POV truth or retcon.
I have a great number of worries when it comes to TROS, Reylo happening isn’t one of them. Reylo was never a thing in the narrative of the films. At best, it was Johnson just trolling and gaslighting, at worst it was Johnson baiting because he’s a troll, but knowing he could never do it because no one would sign off on it anyway. I don’t honestly think Johnson cared about anything other than leaving his mark anyway. He seems pretty uninterested where the story goes now that his time in the director’s chair is over.