As you may notice in many games such as SMS, SM64 or others with "Worlds", there are runs of IW (Individual Worlds). So i suggest having a spot like level leaderboard or full game leaderboard for these types of run as they aren't level runs neither full game runs. Runs like Master Sword could be there, as it is a segment for zelda games. But, as you know each community will work as they want.

couldnt you just do that as either an IL category or as a misc category?

"as they aren't level runs"

What exactly makes a "world" run different from a "level" run? Semantics aside I'm pretty sure those are the exact same thing.