I'd probably say no, if only because by making allowances to ground scale, where a single "model" might represent 10/20 actual men, the single polystyrene hill represents a series of different complex gradients and rises etc.
I think it would be possible to fire a cannon ball up hill and have it bounce, but only if the muzzle was aligned to the same gradient as the "hill", and ball would bounce if it landed on the summit.
I think for wargaming purposes being as battles rarely take place on golf course fairways it fair to abandon realism for the general feel or effect, being on an elevated and exposed position would make formed infantry easier targets for artillery, so maybe keep the "bounce" effect from the rules set even if that's not what's actually happening...