Hate double posting, but no delete and this warrants a new post I think.

Just saying c2p-oh, but the world is basically post-apocalyptic now from how I read it, with Grimm having overrun most bastions of humanity. Given Nahbi's complete lack of experience, it's a stretch to think she could have survived in the wilderness by herself to make the trek across the kingdoms.

That aside, Gram is located on an island so there's not really a way she could have just walked to it, and there's a massive 5m tall wall around the entire Academy.