One thing that should not be overlooked when comparing the system with other rpgs is that conditions isn't exactly the same as hit points. When you miss a roll you don't only loose "hit points"/ conditions, you actually fail and something bad happens. And you can't do the same thing again, if you don't press the roll. In some fights the entire fight is done in one roll, another fight is played out step by step, whatever seems most natural to the group/ the gamemaster. The Kids seldom go alone into deadly battles with a number of foes, but if they do, and the grupp seems to think that the fight is importent enough to get a lot of time and focus, I would let the player roll several times, first to get a good hit on the leader with the nunchucs, then to dodge an attack with a hammer and so forth. And when the player misses she actually fails, and sometimes she also gets a condition. This means the fight could be over in one roll, if it seems plausibel. The Kid doesn't manage to dodge the hammer to her head, and when she wakes up she is lying on the concrete floor, alone, freezing, and the bad guys are gone and they stole her robot.
The way Cwilsontrull describes it could also be a good way to handle a fight, a beaten foe for each Effect. And the Gamemaster could actually also say that it's impossible to win a fight against several older foes and describe how they beat the Kid to pulp and take her stuff.
A good thing to do if the Gamemaster want's the game to be harder is to demand more successes. The Kids need two successes to jump safely from the burning house, not one. And don't be afraid of hard consequenses, they could actually become new Trouble. The robot helps the Kid and all seems good and dandy, but later it stands outside the Kid's house in the middle of the night, it seems to follow him around, and when his older sister yells at him the robot comes bursting trough the wall attacking his sister.
And, as someone wrote, this is more of a narrative game than a crunchier one with focus on numbers and tactics. The important stuff is what the Kids feel, what they do, how they do it. Most often they will succeed with solving the Mystery, but what does it cost them?
(Sorry for any miss-spellings, I´m writing with my swedish phone which keeps "translating" words to swedish, it's a mess...