Knowing how biomes in Stonehearth work, I don’t think this would be possible.
Essentially, Stonehearth generates worlds using Simplex noise. It’s oftentimes used for creating heightmaps, but when used with biomes, it creates a kind of “band” pattern. Consequently, with the way SH generates worlds, you can’t just sprinkle microbiomes in there.
Although there might be hope – Bruno has made a desert oasis mod, as well as tiny islands in his Archipelago mod. I don’t know exactly how that works, but I guess it could be applied to this as well.