Have you taken a look at Saski? It is overwhelmingly full of primary source material, taken from the archives in Paris, and definitely states in tabular form on page 496 that there were 54 8-pounders and 28 4-pounders with the Army of Germany at the beginning of the Campaign of 1809. There were only 8 6-pounders. Further, there were 22 6-inch howitzers and only 4 5.5-inch howitzers on hand. There were 14 12-pounders. Of the 130 field pieces available, the overwhelming majority were apparently Gribeauval field pieces and not AN XI.
As an additional interesting piece of information, there is a table on page 247 clearly showing that 8-pounders were assigned to the horse artillery of the Guard.
There is also correspondence from and between Davout, Napoleon, Oudinot, Songis, the Minister of War (Clarke), Massena and other commanders as well as Daru. It is an invaluable volume and I intend to get the entire set for 1809.