James Arnold was about 70 years late.
Oman’s essay The Battle of Maida was originally published in the Royal Artillery Journal. He corrected his view in this essay, that the French were entirely in column, in Wellington's Army 1809-1814 (London, 1913).
This is what Oman said in 1913.
“Till lately I had supposed that Reynier had at least his left wing, or striking echelon, in columns of battalions, but evidence put before seems to prove that, despite of the fact that the French narratives do not show it, the majority of at least of Reynier’s men were deployed. This is borne out by Bunbury’s narrative, p244, where it is definitely stated, as well as Boothby’s, p78.” (Wellington’s Army 1809-1814. p78.)
On the other hand, Joseph Anderson, also a participant at Maida, wrote that the French were in “formidable columns”, and that when they came under fire from the first British volley they started to convert into line, which is more or less what we would expect I think (Recollections of a Peninsular Veteran, London, 1913. pp12-13.).