Isn't Frank Richards insanely powerful? that he created a small universe as a kid..
But I know nothing of Bernkastel so I won't comment.
Franklin Richards get eaten by ten quadrillion cats. I am not kidding.
Bern is universal+ and is an abstract concept. She was tanking big bangs and big crunches with another universal abstract. And she uses probability magic with the power to accomplish anything as long as the percentage of success isn't zero.
I heard Franklin in the future was universal level as well. Resurrecting Galactus and defeating a Mad Celestial although I suppose Franklin in the future is a low end one if he is.
Bern isn't just universal, she's casually universal being able to spam both the creation and destruction of universes like nothing.
Thrown in her probability manipulation and reality warping and she easily take out Galactus at least without the UN that is.
Not sure about Franklin's max potential tho.