"Nobody knows what they called Him." This is called isogesis, my FRiend. The assumption that you are maintaining is that your conclusion is already true and you will inflict it on Moses as he pens Genesis.
Interestingly, he did not write it that way. So, unfortunately, the burden of proof is on you to demonstrate that when they "called on the Name of YHWH" they did not actually call on the Name of YHWH, but called out, "I DON'T KNOW YOUR NAME but I AM CALLING ON YOU". Hmmm. Peculiar hermeneutic.
Nope. My exogesis of Genesis is in harmony with orthodoxy. The worshippers of God began to distinguish themselves. The margin reads it,
Then began men to be called by the name of the Lord, or to call themselves by it. Now that Cain and those that had deserted religion had built a city, and begun to declare for impiety and irreligion, and called themselves the
sons of men, those that adhered to God began to declare for him and his worship, and called themselves the
sons of God. Now began the distinction between professors and profane, which has been kept up ever since, and will be while the world stands.
Moses wrote in his vernacular. He was not saying that they used "JHVH" specifically.