Hey Kinderfeld. You haven't replied here in a while, but I'm hoping you see this.
You missed the mark when trying to fix the issues that appear when the player is on Kallie's path and not Laura's. I mean, what you did works for that specific scene in chapter 12, but there's a bunch of other places where the dialogue is still messed up because the script was—is—consistently checking if ch10_tell_Laura == "yes" to see if the PC told Laura that he's in a relationship with Kallie, but that variable isn't set to "yes" except in the branch where he's also intimate with Laura. You just need to fix that (and undo the change you made to the conditionals in the ch12 scene) and all the issues will be taken care of.