There are so many Forsaken everywhere, particularly in Tranquillien is when it really hit me. Why did they all come here? It’s nice to see they’re getting along so well, but is there an explanation as to why they settled in Eversong? The Sylvanas cult was also interesting-but when did that happen? Do they think Sylvanas is dead and are trying to resurrect her? Just trying to portal her out of the Shadowlands? Do they want to turn her into a Lich Queen? It would be nice if there were a mini comic or something providing some background.
There have been Forsaken in Tranquillien since TBC. The Forsaken were the primary ally helping Quel’thalas deal with its problems at the time and they essentially ushered them into the Horde. It’s not surprising that some of them stuck around afterwards.
There’s no real lore on the Forsaken you murder in the Windrunner Spire dungeon other than “they’re looting artifacts related to Sylvanas and that makes Lirath’s ghost sad, because he wants you to loot those artifacts.”
They’ve always been there since TBC, Tranquillien was jointly run by Sin’dorei and Forsaken residents as part of efforts to fight the Scourge in the Ghostlands. The original leaders of the town from TBC can still be found there, though it seems that they’re no longer in charge now that the Scourge aren’t a constant threat from Deatholme and the Dead Scar.