It's not a bug, if you apply bound to layout to the bird and let it move every tick to self.x+10 you will see it move across the screen and get 'stuck', this is not stuck but simply bound to the layout. The action wants it to continue out of the layout but the behaviour stops this, the same happens when you apply physics, the physics wants to push the bird out of the layout but the bound to behaviour stops this again.
For the other question, you could disable collision of the object until it is in the layout. There is an object condition 'is outside layout', you use that to disable collision, then you use the same condition inverted so technically 'is in layout', you enable the collision of the object. This would see it drop through the border wall.