55 is a good sized group for a 2d side scrolling rpg, thats being written by outside writers and doesnt have to make the majority of the art assets from scratch.
Then again Im not sure how 50+ people really means in a game. And we dont know how long they have been working on it.
So, what do I know. lol
Its around the normal size of a Obsidian game. F:NV for example had like a little more than 60 on it at Obsidian overall (I atleast think so from last checking the credits)