I may have to rewatch that arc -- which isn't a problem, really, because it's one I actually enjoy watching -- because now I'm not entirely sure exactly how it went.
I'm trying to put the story in order and figure out how to make it make sense. It starts with Regina sending Hook to kill Cora. Cora threatens/tempts him into abandoning Regina and joining her. She tells him about Regina's curse that will send everyone, including the Dark One, to a world without magic, where the Dark One will be a killable mortal. The catch is that anyone who gets caught in that curse will lose their identity and memory, so Hook wouldn't know he wanted to kill Rumple. Hook and Cora go back to the Enchanted Forest, and they fake Cora's death, making Regina think that Hook carried out his mission. Just before the curse hits, Cora creates a magical shield that protects her and Hook from the curse. They'll still be frozen in time, but they'll remain where they are and keep their memories. When the curse is broken, they can travel to that other world, where Cora will be able to confront her daughter and Hook will be able to kill Rumple.
When time starts moving again and Cora's bubble comes down, the people who were caught in that bubble find themselves having to deal with the ogres who moved into the Enchanted Forest after all the people were taken away.
And here we run into some problems with later retcons. In season 2, they made it look like the Coradome wasn't all that big and didn't contain many people. They seemed to have really been frozen, so they weren't really aware of the passage of time and weren't able to go anywhere or do anything. Time did seem to be moving outside the dome, and thus the ogres who had 28 years to establish themselves in the former Enchanted Forest. But then it seemed like the Coradome covered the rest of the world because time was frozen everywhere. Nobody except our world outside Storybrooke and the Wishverse (and possibly the Disenchanted Forest, since WHook was there during most of the curse years, and he wouldn't have aged ahead of Hook Prime, in spite of being from the Wishverse, if he'd been in a place that was frozen) seems to have moved forward during that time. All the Wonderland spinoff events spanned either end of the curse, and none of those people aged 28 years. And then we learned that the dome was big enough for Hook to have sea adventures.
Which makes me wonder what would have happened if Cora hadn't made a dome. Would the entire population of that world have been brought to Storybrooke? It was already a bit much that several kingdoms landed in this small town, but would Regina have taken the whole world? If not, then why couldn't the Charmings have gone into hiding somewhere else in the world?
Anyway, back to Cora ... She seems to have set herself up as the leader of the settlement where the people who were in the dome gathered after time started moving again. I guess she wasn't well known in that world, so they wouldn't have known she was a terrible villain. But Captain Hook might have had a reputation, and it would have hurt her benevolent leader reputation to have Captain Hook as her sidekick, so he had to pose as a wounded blacksmith. I guess she didn't have a firm plan for getting to the other world until Emma and Snow showed up because they went months without doing much of anything. They didn't try to get the compass to have it handy, didn't try to find a magic bean. But then Team Princess comes on the scene, and Cora gets enough information to go after the wardrobe. Then for some reason, she slaughters everyone in the settlement, and either she and Hook plot for him to pretend to be a victim so he can infiltrate Team Princess and get them to help him get the compass (and thus cluing them in about what they need to do to get to Storybrooke) or Hook gets freaked out about her slaughtering the settlement and comes up with the idea to join Team Princess and get to Storybrooke along with Emma and Snow. Neither of them make a lot of sense. The plan idea is dumb, but then why would Cora have allowed Hook to get away from her and team up with the enemy the way he did?
Either way, the plan fails because Emma doublecrosses Hook and gets the compass, and Hook wins his way back into Cora's favor by getting Aurora's heart.
There seems to me to be a lot of extraneous nonsense going on for people who have the firm goal of finding a way to get to Storybrooke. They waste a lot of time with scheming when they could have just gone straight there. And, as with so many villain schemes, they fail to prepare properly, waiting until the rest of their plot is in place before they bother to get all the things they need. If they'd already had the compass (taking care of that in the months between time moving again and Emma and Snow showing up and guiding Cora to the wardrobe), then as soon as they got the wardrobe ashes, they could have taken off without Team Princess having any idea what was up.
It is possible that there's a middle ground, where he was in on the plan for him to infiltrate Team Princess, but the slaughter came as a shock to him, like it was a bit extreme as a way to set him up as a victim so Team Princess would trust him -- so maybe Cora's first act was to magically bury him under rubble, then she set about her slaughter. He seemed genuinely freaked out when they found him, so maybe he hadn't exactly been in on that part of the plot, even if he was part of the scheme to set him up to join them. He was still a witness to the slaughter, but maybe not endorsing it, and there wouldn't have been much he could do to stop it if he'd managed to get out from under the rubble.