Quoting Steve Litt (slitt@???):

> When I added four opennic root servers to my unbound's root.hints

{laughs}

Oh, you sweet summer child. Experimenting with alternative DNS roots,
eh?

It's been decades since I've done so, but ISTR that the correct way to
do that is to re-point the root-hints line in your Unbound conf file
to opennic.cache.

> I'd really like to have both icann and opennic root servers in my
> root.hints.

No, you don't.

opennic.cache should include the standard TLD nameservers.