Berthe de Reims - Married her brother????

Considering what canon law had to say about *that*, I would think it highly unlikely.

She's apparently way out of place anyway ("father" died in 793 but she wasn't born until c. 825, and her "children" were born before she was).

The birth date may be the thing that's out of whack. But as usual, this needs finding the sources on which the family is based.

Would it be helpful to check the profile of her supposed father?

That poor man is a magnet for fakes.