Whether or not the use of grade level word groups or families for teaching reading and spelling is pedagogically sound is something I continue to consider. For now here they are, we use them. They are useful for remediation. Grades 2 and 3 are not yet in sound families or any logical groupings (which kind of seems strange but these are the district lists we have). I have ordered the grade 1 list into a sequence and into sound groupings that make sense to me.
Does your school district suggest a list of benchmark words for reading and spelling in French Immersion?