I dont want to go all "why dont they just turn balls into planes and fly up" but in a 10m deep ditch, with a group of 7 they really couldnt think of riding their nearly omnipotent balls to go up again, or when they were being bombarded with projectiles building a shield from their balls etc.? I feel these kinds of very obvious plotholes will keep popping up since the premise author established revolves around an imagination powered ability but these kinds of premises where possibilites are nearly endless only work when author himself is willing to/able to put in the effort and imagination to atleast include/exclude plausible scenarios from the story. Long story short lazy and unimaginative story writing will probably be a downfall for this series.