I'm just referencing what's actually in the game as opposed to making geopolitical suppositions about a sandbox.
ETA: I would also point out that Khelbun Blackstaff was involved as he authored the surrender letter that can be found outside Reithwin. I wouldn't label him ragtag.
That doesn't make much sense. If Khelben was involved there wouldn't have been much of a battle.
Either way it means the Ketheric conflict was between 1367 (Khelben resigns as Lord of Waterdeep) and 1370 (Khelben is expelled from the Harpers). So 130 years before BG3. Not sure if there are in game documents dating that war.
Either way, back to the blighted village, why was it never resettled in those years, considering how close it is to Elturel? And where did the fishermen come from?