There is, I think, no difficulty in Ex. 6:33And I appeared unto Abraham, unto Isaac, and unto Jacob, by the name of God Almighty, but by my name JEHOVAH was I not known to them. (Exodus 6:3). If we compare Ex. 3:14, 15,14And God said unto Moses, I AM THAT I AM: and he said, Thus shalt thou say unto the children of Israel, I AM hath sent me unto you. 15And God said moreover unto Moses, Thus shalt thou say unto the children of Israel, The Lord God of your fathers, the God of Abraham, the God of Isaac, and the God of Jacob, hath sent me unto you: this is my name for ever, and this is my memorial unto all generations. (Exodus 3:14‑15) we find there, "Jehovah, the God of your fathers." It was the personal name of God as having to do with men, and particularly with Israel—man in the flesh set in relationship with God. It is His abiding name as to this world, either who was, and is, and is to come, if we take Him historically, or more perfectly as in Revelation who is (ὁ ὤν), and was, and is to come, the ὁ ὤν, the existing one (atta hu), and past in time, and to come. But in Ex. 6:33And I appeared unto Abraham, unto Isaac, and unto Jacob, by the name of God Almighty, but by my name JEHOVAH was I not known to them. (Exodus 6:3) it is different. It speaks of the character in which He revealed Himself in order to their walking before Him. And note, when the revelation of Shaddai, as the name to be owned in walk took place, it is said Jehovah appeared unto Abram; and the word was, "I (Jehovah) am El Shaddai; walk before me." Hence, in Ex. 6:3,3And I appeared unto Abraham, unto Isaac, and unto Jacob, by the name of God Almighty, but by my name JEHOVAH was I not known to them. (Exodus 6:3) "I am Jehovah; and I appeared unto Abraham (ב) as El Shaddai: (in) my name Jehovah was I not (made) known to them." This refers to the appearing to put them according to the nature of that revelation in relationship with Himself: so to Jacob (Gen. 35:1111And God said unto him, I am God Almighty: be fruitful and multiply; a nation and a company of nations shall be of thee, and kings shall come out of thy loins; (Genesis 35:11)), as soon as God revealed Himself to him. To Isaac, who stands connected with Rebekah, the risen head of the church, He is not revealed by any name.
The historical name is always Jehovah or Elohim. The One who appears is always Jehovah; but He appears to Abraham as El Shaddai, and so reveals Himself as the ground of, and that which gives its character to, his walk before Him. But it is always Jehovah who appears, as in chapter 12:7. In chapter 15:7 it is no appearing. The word of Jehovah came to Abraham and said, "I am Jehovah that brought thee out of Ur." And in Psa. 91, the title of Shaddai is used as the expression of almighty protection; the Messiah says as knowing the true secret of who the Most High is: "I will say of Jehovah," etc. And so He is kept by the power of Shaddai. Thus, I judge, that though Jehovah, as the expression of the constant being of God, was taken as the specific covenant name of Israel's God—the God of man in the flesh who had to say to God—yet it was, as the name of constant being, the abiding historical name of God. Almighty and Father are special names of character and relationship taken with those to whom God is so revealed. The name of the one true God, the name of the being, is His abiding name, in relationship with the earth—the name. The Israelite had "blasphemed the name." Most High is another relative name taken. Hence it is only in the millennium fully. But it is still Jehovah who is the Most High. Hence you would not have 'the angel of Shaddai' or of the Father, or Elion, because he represents His power as such, not a name of relationship; but he took His name, as the name of relationship with Israel.
It was not that the name of Jehovah was not known as the proper name of the true God, but that His making Himself known to them, as the One before whom they were to walk, was in another specific name. He did not take His name, His own name so to speak, as the name by which He was to be in relationship with them. It is a very important circumstance as to Israel that God's own name, what I may call His personal name, at least in connection with man on earth, "the name" became the name of relationship with that people. Hence in celebrating that name, even in the wide extent of the unopened glory, in the past which belongs to earth, we have (Psa. 8), " O Jehovah our Adon, how excellent is thy name in all the earth!" He had set in that His glory now above the heavens. Elohim is the One who stands in the position of the divine being. Jehovah is the personal name of Him who truly is so. He became the Elohim of the Jews as a nation who had been called out of the world to and by Him when idolatry had come in. (Josh. 24) Jehovah, He is Elohim. And now we say, Father, the only true God, and Jesus Christ whom He has sent; but withal of the Son, He is the true God and eternal life. When it is said "then Jehovah shall be my Elohim" (Gen. 28:2121So that I come again to my father's house in peace; then shall the Lord be my God: (Genesis 28:21)), we must refer to verse 13, whence Jacob drew that which he then said, and so verse 16. But in Ex. 6:2,2And God spake unto Moses, and said unto him, I am the Lord: (Exodus 6:2) we have equally, "I am Jehovah." But in Gen. 35, when Elohim reveals Himself to Jacob as the present God with whom he had to do, it is again (ver. 11) El Shaddai. Jehovah is found in chapters 31:3; 32:9. In a word, Jehovah was not unknown to their own thoughts or in intercourse; but it was not the name He took in relationship to the patriarchs in their character as such: it was with Israel after the bush.