Okay, I'm going to try to explain my take on why I think Eloise has been putting so much effort into making things happen the way they are "supposed to". This is long, and I already know this is going to sound rather confusing, but here goes.

First, Eloise does know that the past can't be changed, i.e. whatever happened happened. Whatever happened, however it happened, is how it always happened. In addition, she also understands another concept, which is that for the people who have not experienced or witnessed how something happened, from their perspective, they still have free choice. They can choose to do whatever they want, but the outcome will end up being whatever has always happened. It's only a free choice to that person because that person has no idea what the outcome is going to be. This is why Daniel told the group when they first arrived in 1974 that nothing they did would matter, because whatever choices they made were what always happened. They simply had no knowledge of which DHARMA people and which Hostiles lived or died, so they didn't have the opportunity to change any history that was known to them.

Now, where it gets confusing is when you have vague knowledge that something happened around a certain time, but you don't know exactly how it happened. For example, if you met Ben Linus in 2004 and then travelled back to 1977 and met 12-year-old Ben, you would know that this kid will eventually grow up and become the leader of the Others. Then if you see that kid get shot, you know that he somehow survives that gunshot wound, but you don't know exactly how at that point. You can choose to do a number of things, but the only thing you know for certain is that no matter what you choose to do, a chain of already-established events, which you may or may not be a part of, will lead to Ben surviving that gunshot. Eloise interprets that as "course correction", but it's really more like false sense of free-will in a predestined set of events, in that you don't know the immediate ramifications of whatever choice you make, but ultimately the choice you make will be the choice that you always made.

Now, getting to the reason why Eloise tries to make things happen the way they are supposed to, it gets even more confusing, but I still think it makes sense, given what I've established in this theory thus far. Suppose I was really bent on changing the past. Even though I've met Ben Linus as an adult, I go back in time and meet him as a child, and I decide I'm going to kill him. Because the past can't be changed, I will ultimately fail. Even if I'm somehow a better shot than Sayid, or say I decide I'm going to walk right up to young Ben and shoot him point-blank in the head, something he couldn't possibly survive, something will stop me from doing that. If it didn't happen, then it can't happen. This is where it may seem like a form of course-correction, but it's really the way it always happened, and my attempt at murdering young Ben is just a part of history that has already happened, and I simply never knew it until I went back and lived it. Now, given that, the question is, what happens that prevents me from carrying out my futile mission? I, of course, won't know until I actually try it, and it could be something as benign as my gun jamming up, but there's a good chance that it could be something catastrophic that happens to me, like suffering a heart attack before I can pull the trigger, or getting struck by lightning. Since I don't know the immediate outcome of my actions, but I do know that young Ben won't be killed, the smart thing for me to do would be to not even try to kill him, because if I do, then something will prevent me from doing so, and it's best to not try to find out.

So what Eloise is doing is basically taking the path of least resistance by helping things along toward events that she already knows took place. In the days leading up to the Oceanic Six return to the island in 2008, she already knows that some of them ended up on the island in 1977, but she doesn't know the details of how they will end up on Ajira Flight 316. So when Ben tells her about his complications with convincing them to go back, she knows that one way or another they will still end up on the island in 1977, but if it doesn't happen the only way she knows how to get them back, then something drastic and unpredictable will happen instead. This is why the only response she can give is, "Then God help us all." If she and Ben don't succeed in their mission to get them back, then she doesn't know how they will end up going back, and she doesn't want to find out.