I am not seeing the frost on them my self. Frosting normally happens to alloyed lead. I have never seen soft lead ( 5 BHN to 8 BHN) frost. In the middle picture the two balls on the left look like they have a tint of blue. That to me looks like soft lead and no frosting at all. They are wrinkled bad but I don't see frost.

To the OP. I am with the rest. You need to just clean the mould good. Get the lead, and mould hot. If it is a bottom pour pot make sure your getting good fast flow from the spout. Slow flow from the pot or ladle with allow the lead to cool as it is going into the mould. That will also cause wrinkles.
Speed up your pouring, and grade them after you have some done. After you get better you will be able to grade as you go but it will take time. For a while just pour some balls and get used to the whole thing. Ron