The Laws of Magic aren't directly related to the Accords.
The Accords are about how different supernatural political groups interact with each other.
The Laws of Magic have to do with the limits of what mortals can do without monstrous consequences (either making themselves a monster or unleashing a monster).
They are like apples and oranges.
OP's question: "Does an Unseelie Knight have to respect the accords?"
My answer: All members of the accords have to respect the accords unless...
1. They don't care about causing a war.
2. They don't plan to leave witnesses or evidence that the accords were breached.
3. They don't care about being thrown under the bus to "make things right."
But this whole "Sponsored Magic and Lawbreakers" discussion has gone way past the point of being productive (and it has nothing to do with the subject of this thread). It really comes down to two points of view.
A. You want to allow sponsored magic to be an out for mortals to violate the laws.
B. You don't want to allow sponsored magic to be an out for mortals to violate the laws.
Those that feel that A is correct will keep saying it is, and those that think B is correct will keep saying it is. It's called disagreement and it is perfectly acceptable to disagree.
Just sit down with your own group and discuss it. Way more productive. Just focus on the implications.
Under B, Sponsored Magic means you can only "borrow" fate points to invoke for your magic (and your magic might count as something special for satisfying catches if applicable). If you go this route, it is really only valuable if you find yourself in situations where you have no fate points but could REALLY use an extra fate point (or two). If that never happens, you probably don't need Sponsored Magic.
Under A, Sponsored Magic is WAY better. Assuming you would violate the laws of magic on at least 2 occasions, Sponsored Magic was a good investment, and you can still "borrow" fate points if you find yourself out of points (or want to save points for when you might be compelled).
This topic will never be "resolved" short of a "Word of God" being handed down by Jim Butcher or the Evil Hatters. Since they have all been absent from this argument, I am guessing they have no plans to jump in now.