They are not total failure. The scientist said all children were modified successfully on paper, but Sanji failed to awaken genes. It doesn’t mean genes do not exist at all, it means the genes lie dormant inside. They are awakening extremely slowly probably.
Dj?fire? No mera2 no mi, no haki, no spin. The only way to explain it is his modified body. Power of science.
Ashura? Just an illusion from Zoro's strong aura.