If I'm not mistaken, the artillery dice gets used to show the distance of how far the template scatters ( if it doesn't hit). But on the page earlier in the BRB it shows 2 regular dice used to show the distance.
Do we scatter with the artillery dice or two regular dice?
Artillery dice always, unless the description of the warmachine says the opposite, but in this case, artillery dice.
I had to look in the BRB. The reason that diagarm is using 2D6 is because the example is a 2D6 scatter.