Garbagio Engine, no offense
Real sorry to have to say this dude, but you have two majorly amature glitches in here. Notice that if a ball is at all below a circles midpoint, and then bounces towards it's center off of the top of a seperate circle, it will pass directly through the wall. The same is true for a ball within a circle that has enough force it reach the roofing above it (the upper half of the circle's interior)
A second glitch, balls that land on the top of a circle, and begin to slowly bounce off, may in fact bounce back up a single time before falling down again.
Good luck with the engine.
and if it helps at all, linked an awsome tutorial below