Have you located this town (St. Jean de Leon), which you've spelled several ways, in a French Department and province? I looked and couldn't clearly identify it. That's the first step to finding documentation in France. From my experience, records are often found recorded in nearby towns in the same Department. Have you checked Geneanet.com and the LDS' Familysearch.org, including their microfilm catalog. Both of them have many more French records than Ancestry.