"When kolto was replaced in favor of bacta, the Republic abandoned Manaan, and the Selkath left Ahto City for their ancient cities in the depths of the planet's oceans. Manaan did not have further contact with the galaxy until the Selkath were enslaved by the Galactic Empire sometime during the Galactic Civil War."
"Bacta was invented by the Vratix on the planet Thyferra in antiquity, with the galaxy at large learning of its properties around 4,100 BBY."
4,100 BBY = Year 447 before the Treaty of Coruscant (BTC)
Sorry man, probably no Manaan :/
Yeah, I read up on that right after I posted, but still kolto is referenced several times in the game (kolto tanks, kolto injectors, ...), whereas I haven't seen a single mention of bacta. Which would mean that kolto is still in wide use at the time of the game, which would still make Manaan a viable location.