I would guess that they have never existed, and never will in terms of the actual dresdenverse, but I also don't see a major problem with someone creating and using them in their version of the dresdenverse (though I wouldn't want to).
It is pretty standard in most faerie related stories to have the Seelie and Unseelie, with the Seelie being the "good" side, for certain values of good, and the Unseelie being the "evil" side, for certain values of evil. These sides are not always depicted as "Courts" and/or sometimes there are multiple separate courts that are on each side. Jim has just chosen to use two courts and call them Summer and Winter, Seelie and Unseelie, respectively, which is fine by me. Makes it way simpler.
Aside from these two sides (Seelie and Unseelie) there is rarely anything else other than straight up wild stuff and maybe some minor powers that are semi-independent, or very major powers that just kind of ignore the Seelie and Unseelie (because they don't care) and are ignored in return because it is not worth the effort of bothering with them. These are the sorts of powers, both the minor and major ones, that the protaganist might turn to for assistance if they are in trouble with the Seelie or Unseelie. However, in the process they often gain a major debt that complicates their lives for a long time to come.
So in most faerieverses anyone else that sets up a "court" is going to probably get crushed in a seconds by Seelie and Unseelie, mostly based on who gets there first. The only way to survive would be to be powerful enough that neither side can afford to destroy you on their own, but even then they will probably just band together to destroy the upstart, while also trying to gain advantage against each other.
So I personally do not like the idea of autumn and spring courts, and if I were GM I wouldn't allow the players to "create" them, and if I were a player I would argue against other players being allowed to create them. However, I would allow or suggest someone to be beholden to another power in the Nevernever, which they could make up themselves. This would give the player a LOT of options, while also being much simpler to manage and fit into the universe. A single powerful entity is a LOT less complicated than an entire court after all. What would be even better would be if they thought they were beholden to a major power, but it turns out it is fairly minor, just powerful enough not to be bothered, but weak enough that when the PC tries to use their "status" with this power to intimidate someone like the Summer Knight they get laughed out of the room... Suddenly that "deal" they struck doesn't seem so hot after all, but it is too late now!