Almost no one in the world had ever seen an actual dragon as they had been gone from the world for over tens of thousands of years and were only vaguely mentioned in history.
They were now largely seen as myths or fairytale even in a world as mystical as theirs.
However, being Devils that had gained consciousness from almost the very beginning of the omniverse, both of them had actually seen and encountered Dragons at different periods of their lives, and Lilim had even fought a living Dragon that had somehow entered the Underworld.
She had lost, of course. They were Dragons; even the weakest among them were above most Demigods, much less the one she faced. However, that incident had given her a comprehensive understanding of the powers and experience of that Dragon, and she had used that knowledge in her creation.