Is “Luo Yi's son, Cold-faced Cold Spear Luo Cheng” true?

In 'Romance of the Sui and Tang Dynasties', the 'Cold-faced Cold Spear' Luo Cheng shines, being a cousin of Qin Qiong and leaving behind many legendary stories. However, in official histories such as the 'Old Book of Tang' and the 'New Book of Tang', there is no such person as Luo Cheng at all. He is purely a literary figure invented by folk artists and novelists to enrich the heroic lineage of the Sui and Tang dynasties.