There is no need to have a confirmation to edit/add categories to a game. If they take a week to add the categories they are probably busy in real life or they just forgot.

Hard to say when you haven't specified what game it is. If it's an obscure game with one mod, they're probably just blowing it off. If it's a well-established game with a big community and a team of moderators, it may be the case that they find the idea interesting, but need to discuss it and get the opinions of those in the community. Big communities won't change the setups of the leaderboards just because one person requests it.