Two days ago I requested a Super Mario Bros. ROM hack from the "Request game" button from the Super Mario series page. It got rejected yesterday and I was told to submit the request to the moderators of the Super Mario series, but the problem is, when I go to the page it doesn't display who the series moderators are unlike with most other series pages on the website. Do I need to specifically message a mod from the SMB1 leaderboards?

If it's a New Super Mario Bros ROM Hack, theres a seperate series for that, contact them: https://www.speedrun.com/nsmbhacks Im not sure about the NES ones either, Id say try resubmiting it and explain that in the additional notes section

I think I remember hearing that the mario series specifically doesn't have series mods because of the sheer amount of games and sub series. I guess that Mario Series serves as an umbrella for those sub series so those can form their own communities.