Looking only at Sorceress and Magician, both being bred to Buckbeak, what can I expect? (Not looking at the C and E gene for now, as that brings the possibile combination to 243 different combos). Focusing on the only A, B, and D:

Sorceress

Sorceress AabbCcDdEse

Buckbeak: AaBbCchdcDdE_

In the future, a pairing with Sorceress and Buckbeak should have 75% Agouti that has a 50% chance of being black or brown, and a 25% chance of being a cool, diluted color. I don’t really want to calculate the complicated triangle now, but getting a fun, yellow colored kit from Sorceress involves being brown AND dilute is 12.51%. Not including the coloration gene and color intensity gene, which dilutes the risk to a much lower number.

This pairing also has a 25% chance of producing Red Eyed White kits!

What about Magician? 

Magician AAbbC_DdEsE

Buckbeak: AaBbCchdcDdE_

Given Magicians background, it is 100% probable that her kits are Agouti (and they have been), and a 50% chance to be brown, and a 25% chance of being diluted.

It is also very doubtful that this will produce REW kits.