I think you're making it too complicated already. Ethnic City Styles should be a module in VD, which already contains all the XML. The way modules work is that if a module contains an XML file, it overrides the contents for those XML tags in the base mod, so there is no need for overriding and explicit copying. So just copy Varietas Delectat/Assets/Modules/Ethnic City Styles to K-Mod/Assets/Modules/Ethnic City Styles.
You might also need to migrate Civ4PlotLSystem.xml and Civ4CityLSystem.xml which aren't part of the module, iirc.