They are lavender, but I have my doubts as to whether or not they are first Gen crosses. As far as I was aware, the mottling genec is not in Marans, so the offspring wouldn't be mottled. Since they also state they are using split lavender Marans, not all the chicks would be lavender either. Are the adult photos you have up there of the parents?
If they are the parents, from what I can determine you wouldn't be getting mottled lavender olive eggers, but a mix of lavender and split lavender olive eggers, probably with some leakage in the hackles. All of them would be split for mottling as well.