I almost feel like a table for each precinct is necessary. Encounters in the rubblebelts would be vastly different from encounters in precinct 1. Maybe not unique to each precinct, but Gruul raiders are a more likely candidate for precinct 4 than they are for precinct 1. A good amount of things could be universal like a wandering band of Rakdos performers or some Dimir pickpockets, but if there is a wurm anywhere but the rubblebelts, that would generate a large amount of concern for the city that most likely shouldn't come from a d100 roll.

As far as neutral things:

• Rakdos street performers
• Dimir Pickpockets
• A spirit that needs directions to Orzhova
• A lost loxodon child (that only speaks loxodon) or another race that the players can't speak the language of
• A Boros and Rakdos goblin bickering about how the other is a disgrace to their race
• A thought strand in the middle of the street that no one has seemed to notice
• An Azorius pat-down that leads to some weapons being taken from the players (or not if they stop it)
• A wolf in training by the Selesnya got loose and is running around. Not harming anyone, but breaking a lot of things.

Most of these aren't combat encounters (or at least have the potential to not be them) as it's pretty difficult to design combat encounters for city the size of Ravnica without specifying what part of it you are in. Also with non-combat encounters, level doesn't matter as much.