All you need to do is to consider the censored scenes. You know, the loli's with the massive racks. That was done by someone in-house in Nutaku. It seems reasonable that the devs were consulted for the complicated stuff like the marriage system, but they were happy to take a step back and let Nutaku handle the localization of the game.
I mean, consider Kamihime's generosity where the Devs have an active hand in the game, and compare it to the skinflint response that Nutaku has with the other DMM titles. Which do you think is the one where Nutaku needs to pony up their own dough?
I can't profess to having the agreements on hand. But you can use logic to consider the history. First of all, Nutaku was founded in 2015. A Canadian company. Not Japanese. Now consider that Nutaku SOMEHOW managed to enter an agreement with DMM and now has the right to host several of DMM's top titles. Either some amazing negotiating had taken place, or a no-name company with a bit of money to burn offered something to those devs. Mainly, they would provide help in bringing those games over to the West. What did that help normally entail? They probably offered to take care of the translation in addition to navigating the legal quagmire and offering the usual hosting service. After all, translation is not cheap. Most Japanese companies don't bring their games to the West BECAUSE it's not worth the cost, not because they're not interested.
But if you keep a few on staff, and keep the work flowing to them, you can basically consolidate the cost. Not only that, Nutaku speaks the language, knows the laws, and they're not a US company (which have a reputation of being pricey). So all Nutaku has to do is claim that they can localize a game for cheap, point to the other game developers that have signed on, have the developers pledge the very basics of tech support. With that, the developers will have the impression that they can sit back and relax and their game will appear in the wider world while money will flow to their pockets. Nutaku is the one who will take care of the heavy lifting.
Here's the rub. Nutaku is a new publisher. It's not known as a translating company, it doesn't have a long list of successful titles. The Canadian company is basically like a Chinese contractor who placed the lowest bid. Trusting in it to make your game successful is basically taking a leap of faith.
...Yeah, the long list of shuttered games shows that the dev's trust was misplaced. Nutaku will claim that it was too soon, and that the Western world was just starting to get used to the idea of anime in games. But most of us know that the publisher's questionable quality, tight purse, and overwhelming greed isn't helping matters at all.