A few annoying gimbal locks has appeared and are making the rough animations a pain in the arse. I've been able to fix the worst locks by switching over to inverse kinematics animations while lifting the cannonball. Also, up until now I've been trying to animate the cannonball as a standalone entity, but manually adjusting the speed and position is too tedious of a job. Therefore, I'm now going with a link constraint solution together with the IK animations. This combination seems to work out great so far. I suppose the gimbal locks could've been avoided with a change in the euler rotation order, but what the hell, this is a better solution by far.
Otherwise, the rough stage is coming together nicely.