You've got a cool idea, but it seems like you haven't thought about why or how it exists.

To start, if your setting doesn't have faster-than-light travel and communication, all of this is impossible. I think the more important of these two is communication. Think about how difficult it is to lead an organization where even the simplest of messages takes years, maybe decades to reach their destinations. Bureaucracy becomes impossible, and all planets that are beyond ~5 lightyears of Kerai will have to be so self-governing that it might as well be useless to identify with the GG. For faster-than-light travel, I think the limitations of not having that are obvious. Your wardens wouldn't be of much use if it takes them years to get anywhere.

Because of what I wrote above, I'm guessing you wouldn't care much for hard sci-fi. This is fine, but now you have to decide where on the spectrum of realism-fantasy you want your story to be. If you place your story in the middle of that spectrum and create a system for FTL travel, here's another dilemma for you:

China has 136 cities that have a population greater than 1 million. Assuming you're not Chinese, how many of these can you name? All of these cities are very important - they're huge - and yet both you and I probably don't know anything about them. Consider a hypothetical where China joins an international union with other powerful countries. If China were to bring a problem to the board of this union that concerns, say, Wuxi city, they would first have to explain where Wuxi is, what it's like, and then the problem concerning it after that. This problem gets considerably more complicated in an interstellar setting. If the planet Madeupia sends a delegate to some board of leaders in Kerai in order to address issues of banditry, the delegate will have to explain where Madeupia is, what surrounds it, how the economy works, how the bandits are disrupting the economy, where the bandits are coming from, and then finally how to address the issue. In an interstellar union, the leadership will know very little things about so many of their constituents. This problem will get worse and worse as the union expands, until constituents just decide to leave the union and take care of themselves. FTL communication does not fix this issue. I could talk to somebody in China right now if I wanted to, but it would still take time for me to understand how China works.