On the second graph, you can see that it was meant to have two engines on the wings. Actually, I think it wasn’t really a canon but much more a conventional dive bomber. If you see it this way, the idea is not entirely stupid, the bomb in the front would help to aim the target and reduce drag during the flight. The spring is needed to relive the bomb und not to collide with it afterwards, but surly not to increase the impact significantly.
What I find problematic it the CG shift when the bomb is relieved, there have been good reasons to mount the bombs under the fuselage with a neutral CG position. To make the concept work, the bomb should be much aft in the current position of the spring. To make room and to save some weight, the spring could be replaced by pressurized air reservoir which could blow out the bomb pneumatically instead with mechanical force.