Audofleda and Bertefleda are recorded Frankish names, so Audoflède and Bertheflède would be direct adaptations into modern French, without intervening modification. Unflat "dirt, filth" from Middle High
German unvlat "dirtiness, untidiness" and unflätig (also "dirty, nasty") from MHG unvlætic "unclean, untidy" are the only certain cognates of *flad in prosaic use, although Norse fleða “sleek” seems likely (if an earlier meaning was something like "trim, tidy"). Norse fljóð "woman", sometimes suggested, appears to be a kenning inspired by the un-related fljót "fleet".