Just spawns a square mushroom island with a small forest in the middle and infinite ocean on Planet Earth setting.
Using 1.12.2 version of mod with 1.12.2 Minecraft Java and CurseForge.
CubicChunks, CubicWorldGen, Journeymap and MalisisCore installed.

That's intentional, you spawn at 0, 0. Use /tpll lat long