I've recently set up a dual-PC singleplayer client with a 6-core laptop being the server and an 8-core desktop being the client, I have not been able to find any sort of config file for Tectonic anywhere even looking into earlier clients before I set this up and my system cannot find anything except for the mod jar. Right now I'm limited to vanilla generation when I wanted to implement tectonic generation and extend the height limit.
Client & server: Tectonic-3.0.0-beta4
1.21.5
Fabric