i remember reading some post i think it was in the shogun total war mod's thread hear is a quote of it. This is what Barocca said. Hope this helps.
'the corpses dont appear because i have not yet made them appear,
there is a bug in medieval that forces the game to ONLY display corpses for units listed in the crusader_unit_prod file, (its way more complicated than that, too hard to explain in detail without access to my notes)
many viking units are listed in that file, some are not,
those that are not will not get corpses.'