If you ask me, you should shorten the list to people who only / mostly concentrate on mania to make it more organized and let people know who they can count on. That's why the
Taiko list isn't so big. Though, beside that, the bigger the group, the more people relay to each other.
Additional to this, if mania really has significant problems (since a longer time?) in the ranking process, you could try something like
this. Having a
Mania Nominator Association with people who are interested and dedicated to bring mania ranking forward. If there is any interest from side of the mania community and BNs, I could try to help you in this matter, as Taiko had the same problems for months, and now our situation has become much better.
Have a picture of how the structure is.