you have hit on two battles where the British artillery was handled with significant effect. The amount of movement of the Allied artillery in general at Waterloo is surprising when one starts to look at it with care. Several batteries engaged from two or three different locations. Others had to be pulled from the line for repairs and replenishment, only to be reinserted later.
You are also correct that the French artillery at Waterloo presents the appearance of being the opposite and quite inelastic. In part this is because a significant quantity of the artillery from I Corps, II Corps and the Guard was committed to the main battery. After it was severely damaged by the British heavy cavalry, it was not fit to move. There has always been the interesting question as to why the cavalry charges were not accompanied by the organic batteries. Between the two corps of cavalry and the Guard, that would have been 8 horse batteries. What is often missed is that the Guard infantry were accompanied by artillery, though it is difficult to ascertain their type and provenance. All told, Waterloo is a bizarre demonstration of command and control by the French at all senior levels, including the artillery commanders. I should like to understand as much about the individual French batteries as I do about the Allied batteries. Certainly, the difference between battles like Friedland, Wagram or Hanau and Waterloo are stark, with respect to creative use of artillery.
Hughes may be slagged by some for various reasons, but I still like his analysis of artillery at Talavera.