The french heavy artillery for sieges never had a 32-pdr. The heaviest siege un the french used was a 24-pdr. Heavier guns were used as coast artillery, cast in iron to the designs of General Manson in the 1780's.
I am not sure what weight of shot the Villantroys howitzers were, these could be the 32-pdrs mentioned as they were unique to this siege. these guns were submitted as part of the French Artillery reforms of AnXI (1803), but not adopted as part of the system. The drawings were used to cast these guns in Spain in 1810. I have the casting dates and orders for their production somewhere.