I would say it would go the same way as it did in nightbringer. Maybe Lucifer would feel something and not quite know what he's feeling yet when he looks at her? Maybe he feels a hollow ache in his chest and doesn't understand why? Or maybe he simply does not react, feel or treat her in any softer way cause as you say, it is past Lucifer and he doesn't know her. But I am inclined to say...he would definitely feel something when he looks at her. Maybe a vague familiarity, or a soul tie, or even an aching love he doesn't understand why he would be feeling for a strange woman. The pair are made to be together in every universe. It is written law. No one else can or will ever be for Lucifer. And no one else can or will ever be for Lya. They are bound to each other in ways that transcend time, space and universes. 🩷