[Sombre]

You might be able to work around that bug by re-restricting the original ermor spell you're copying to ermor, after you've referenced it with your own spell.

So something like

#selectspell Ermorspell
#restricted ermorid
#end

Later in the mod file than your spell based on it. Might work.

If not, you can probably make the unholy spells that you're copying from scratch, rather thann copying them, using the more complex spell modding commands (I was never too hot with these, but the documentation is out there).