Honestly I havn't read the whole thread, but I don't think this has been menctioned before. Not a solution, but a piece or two I think.
Ishukone knows something about this, to the point they have been in a wormhole system before anyone else, probably just once, and certain high placed people know this.
Reason/Speculation:
The chrons Anoikis, Depth of Field, and Ante that Amann linked point to this, saying that Ishukone has experience, or would want data from wormhole systems. This implies that Ishukone knows something about it, but that they also want to know more, so whatever access they had gave them a taste for something there and then cut off.
Ishukone has been known to be able to control Rogue Drones to the point of getting permission from a Rogue Drone hive to access the Insorum in TEA. Later, the Blood Raiders gained more absolute access to a Rogue Drone facility processing Isogen-5 (in the End of the World series). This implies that Isogen-5 and Insorum were both made by the Rogue Drones and stored for some reason, and that, with the link between Isogen-5 and wormholes, that Rogue Drones are related somehow to the Sleepers. Therefore, a bit shaky, but you can follow the chain that Ishukone might know about Sleepers and the wormholes.
Second piece:
CreoDron and the Sisters of Eve/Serps both found out about Wormholes after Ishukone, but I think knew something about them before they opened up for everyone.
Reason/Speculation:
Once wormholes open up, these two seem very quick off the mark to rush into them, though they seem to not know exactly what they are looking for, see the gift shuttle and Anoikis. The shuttle was released to quickly and to purpose built for wormhole exploration and getting all that data back to SOE/Serps for them to not have known anything. CreoDron was similary quick to jump in from Anoikis. This implies they knew something good was there, something worth being ready for a chance. Maybe they found out something from Ishukone. Also, someone told the Blood Raiders, and Ishukone doesn't strike me as a prime suspect for that, so the more people that know means the more people to tell them.
Just those two pieces, but hopefully someone else can build on them.