The mangrove forest seems to not be generating with Terraforged. I have turned the biome weight in Terraforged's configs to a very high value so it is confirmed it does not generate. I have looked through some other bug reports for Terraforged and it seems the biome is not marked for use in overworld. Please fix this bug as soon as possible, I really love this mod and it's a shame it's most prominent feature doesn't generate.