As you note, “restoration site” is not an available designation in iNaturalist. So as covered by numerous other threads here on the iNat forum, if you can tell that the plant is one of the originals placed by a human, it would be cultivated. If you can’t tell, or if it’s clear that the plant is from a subsequent generation that reproduced on its own (without obvious tending, watering, etc.), then it would be naturalized, and therefore “wild.”
I’d mark as wild with a note in the description that it’s offspring from a restoration planting. As long as something is reproducing and surviving on its own without a human tending it, it counts as wild.