Satins are being bred more and more true. They can be pure but just are not recognized by APA. Eventually breeding these satins to silkies and then satin to satin, your percentage of silkie goes up to 99% with is considered fullblood so they aren’t necessarily a mix. As for frizzle, that’s a gene, not a breed so you can’t assume Cochin comes into play as that gene can modify any breed. There are pure silkies with the frizzle gene and that’s made possible by generations of breeding what started as a mix and making it fullblood again. Best bet is to wait and see what the comb, conformation, and adult bird size are.