https://www.youtube.com/watch?v=JpU3WPfdi_8 The truck in real life does not get damaged as quick as in the game.
In-game balls are much bigger and weight more, therefore they are much more destructive also half of the shots on the video were terrible misses.
You are comparing a modern howitzer, whose purpose is to fire a shell (lethal/destructive potential come from the explosive shell) with an old cannon whose purpose is to fire an huge ball (potential come from speed and ball weight). So yes, an howitzer using non intented ammo will do light damage. Though it is ridiculously light. According to fast calculations, the cannon should weight (not including the knob neither the carriage) between 9,7t and 10,6t. The ball between 300kg (hollow) to 1t (full) (Values of similar caliber from Wikipedia). While in game the total flyweight is 1,17t.
