I think traders should be random not biome specific.

On the OP’s question, you’d need a new map one way or the other to get different traders in different spots. An alternative, assuming you’re admin of the server, would be to use the F6 debug menu and simply spawn whoever you want where you want them. For instance, you could go to Rekt’s POI in the forest and spawn a Trader Jen within his trader compound. Then your players could interact with whichever trader they want.

I’m not aware of any dev plans to go back to biome-agnostic traders.