Since this voting system will give an official osu! badge I think doing an official form in the osu website should've been the best way to manage this. It's really tedious and takes a bit of time doing this form manually + finding all the maps... The issue here is that, imo, lot of people won't even nominate or won't nominate more than a few categories and just a few options for ea.
Not trying to devaluate the hard work but doing something more friendly for the people to participate would've been better I guess.
Maybe you tried to do something more official but the staff couldn't do it in time? ... idk. Hope everything goes well though!