Do not worry about the feather color.
Most of my Laced Cochins feathered in dark with almost no lacing at all at the beginning, but today they are some of my most beautiful birds I have. They will go at least through 5 molts until they will have the final beautiful laced plumage. Be patient, your birds look very nice to me already and I cannot wait to see photos when they are a little bit older.
Not sure, but I think I have heard about the seller of your hatching eggs before and he has a good reputation around here.