I think this is a great idea. I am having to renumber things for a mod of my own and failing to do the work largely because of the complexity of checking everything. Such a listing would 'vastly' facilitate the task.
My '
Three Races Mod':
--nationslots 72, 73, 74
--unitslots 2401-2423, 2454-2458
My Warhammer Chaos Mod I'll list once I've done the renumbering.