The Deep Dreaming 1 is a place that amps up a Kithain's birthright to 11. They become the most powerful and dreaming version of themselves.
For example, even the ugliest Sidhe is actually quite handsome in the Autumn World (Base Appearance 3) and becomes so beautiful that it hurts to look at them (Appearance 7) in Deep Dreaming). The most stunning of them that look like this in the Autumn World (Base Appearance 7) and become so beautiful that they'd stun Aphrodite (Appearance 11) in Deep Dreaming. But Sidhe actually are somewhat easy, because their Birthrights are on the more straightforward side 2.
On the other hand, there are cases like Selkies that are much harder 3, as they seem... rather situational. Still, at least Grace of the Sea seems to be manageable: add one type of roll that can't be botched in Far Dreaming and two in Deep Dreaming, reduce difficulties by 5 for any Dex roll in the water in Far and automatically succeed in Deep Dreaming.
And then there's Redcaps 4. They outright don't seem to have a Birthright that could be modified under the rules 1? The Dark Appetite already only needs Glamour for the most heinous materials, and Bully Browbeat... eh... adds maybe two items that can't be botched to the list of unbotchable skills?
You see, it gets complicated easily...
Is there a complementary list of how to handle Far/Deep Dreaming Birthrights and how to modify them for the standard Kithain beyond the rather rough guidelines in the core book that eludes me?
1 - C20 p.301
2 - C20 p.107
3 - C20 p.105
4 - C20 p.103