So Eru, and likely Reiss/Fenris, are transcendent beings of the invaders and interact with God's rules in a weird way due to being outsiders. Eru can bring back the dead, would that imply that the invaders/monster keeper has some authority over the underworld/afterlife if they can call back the souls?
As for the shortlist, it's really just 4 people right?
Mother and father.
The other two would be Sora and Christina, if he and they wanted to break the disciple binding and bring them back as a living person no longer bound to the God's rules as a transcendent. Haruto himself has not liked that they are bound like they are, especially Sora who he doesn't feel like he's the one who bound her. Could this be a way to give her back her life and let her age again?
Lina's foresight might be limited to things native to the world or even be unable to foresee intentional actions of other transcendent beings. It may be a limitation of what data she has when predicting the future and data from outside the world (invaders) or outside of norm for a transcendent isn't something she has. Maybe rather than a target limit being number of people, there's a limit to the number of branches of time she can analyze at once. Or a limit to the probability of such a branch, maybe she can't follow a branch unless it is over a threshold of being probable. Lina might be pushing so hard to get Haruto to act in a certain ways because if he makes choices outside of expected data that it becomes part of a branch she didn't or wasn't able to look at, especially if it's an action that Lina didn't except could be made. The golems could have been an odd bit there because the golems themselves aren't transcendent. Future sight might have just seen the golems suddenly appearing and she extrapolated Reiss' actions from it. Foresight is always a challenge to define because either you have to assume that people's actions either are always preset or have no impact or you have to have 'fuzziness' allowing for the infinite number of decisions a world of people could make and the massive branching that has to occur due to free will.