[Marcello]

There are some artillery pieces equipped with proxy fuzes in the game. They are labelled as VT and have greater HE kill values.
Aside from that they do not differ from normal artillery, they create craters at the same rate etc. As for treebursts, there aren't any, nor probably there could be. I would expect that the germans were getting this effect by regulating their fuzes on "superquick",so to speak. This probably won't be done in many others cases.