Icon naming changes break everything
Why? Why have you changed the icon naming convention? All the themes now needs to be updated to accommodate the changes from "utilities-terminal" to "org.gnome.Terminal". Older themes are broken. New themes comes with a bunch of pointless symbolic links. Even your own icon naming guidelines aren't updated https://developer.gnome.org/icon-naming-spec/#guidelines
Please introduce a crutch fix which would at least try to poke the older naming convention icon file if no new one is found. Of course it is still an unneeded work but it will at least partially fix the mess you caused with this change.