This may be a stretch, but I think that ILs would be cool and would help liven up the leaderboards and maybe generate more interest in custom maps. Obviously the problem is that there are many custom maps with more to come in the future. But I think it will be cool to push these maps to their limits as you don't typically see them that fast in most of the runs. As far as I am aware, the only cases for Pure ILs would be the end of Laughterhouse/start of Solar Limbo (Babe of the Realms) and the end of Crimson Rupture/start of Lost Sanctum (Immortal Babe). Also for Immortal Babe maybe it's better to just stick to the nerfed version and combine Tower of Tartarus and Remember together and just call it Tower of Tartarus. I'd be happy to help moderate if needed.
This feature would show the position that each run was at the time it was uploaded. I know you can filter the leaderboards by the date to find this out, however, I still think this would be cool. Maybe it's best for the feature to be toggleable as it isn't vital information but still cool for the people that want it.
I feel like it would be cool (and easier) if you were able to filter leaderboards by countries (only the ones in which the category has runs for).