Jordan isn't a natural werewolf because she had a different mother than Hunter.
This would provide an explanation as to why Hunter is a natural werewolf, but Jordan is not a natural werewolf. Hunter's mother was a carrier of lycanthropic traits, which were passed onto him in active form; in contrast, Jordan's mom was just a normal woman.- There's no evidence for that. Both are always mentioned as having the same mother.
Jordan isn't a natural werewolf because she just didn't inherit the werewolf gene
It seems possible it's sex-linked in their case, since the ancestor Hunter gets it from was also male. Jordan is a carrier for lycanthropy
Jordan is a natural werewolf of the wrong line
This would explain a lot. This is why Jordan seemed to be cured after the time limit, but also kept her powers somewhat. The artificial serum instead of just making her a normal werewolf of that line triggered her uncontrolled change but not for the first time. The first time Jordan changed was in defense of her brother before they moved to the village. Jordan lost control and had the worst experience possible and ran from it. Whereas Hunter saw the positive side and got obsessed. The cure worked and the poor change both happened because the artificial trigger could not bond properly. Jordan is happier at the end accepting both parts of herself. Paulina has some item that keeps the sunlight from killing her.
Hence, she is still alive at the end even though she got bathed in sunlight.Sunlight can still damage her, which is why she was worried about getting in "before the sun comes up."
Paulina has Plot Armor just like Spike and Angel from Buffy the Vampire Slayer.
Some people are just that lucky.