The usual fate of French WWII dead in Great Britain was to be taken to their French home town after the war, but I can't find anything on Langlois' grave on my usual web sources.
Here is his card in the SGA database listing WWII dead:
http://www.memoiredeshommes.sga.defe...58540&debut=20
As a deceased member of the "Forces aériennes françaises en Grande-Bretagne" (French air forces in Great Britain), a file should be held on him by the Service Historique de la Défense, but I only have data for people starting with letters A and B, I never had time to continue this files.