It's hard to be sure, but I think this entire pondering might well have originated in my head (some years ago) from HP's bad Latin; one of the first questions, if not the first, that made me start thinking in this direction was wondering whether I could possibly justify the bad Latin by an in-universe explanation rather than 'Rowling got it wrong'.

(On which subject I also have to give a shout out to ho for hoggwarts!, for its perfect fusion of the HP spell schema with Molesworth. "But surely sir lumos hav a greek nom. ending whereas the root come from lat. lumen luminis a lite as any fule kno?")

I see that chapter 25 suggests some counterarguments, but then, its version of the concept is more mechanistic than mine was anyway...