According to the map of Amn and Tethyr included in the 2e box set of Lands of Intrigue, Toralth is just SSE of Riatavin and NE of the Eastmost tip of the Forest of Tethir:

[![enter image description here][1]][1]

Tethyr itself is the right at the bottom of your map and I've marked the approximate location of Toralth with a red dot:

[![enter image description here][2]][2]


  [1]: https://i.sstatic.net/372bh.png
  [2]: https://i.sstatic.net/srF6B.png