As other parts have been addressed, I will not restate them. However,
El -> God Elyon -> Most High (El Yon) so not to close possibility that Elyon may be a different God than Yahweh or Elohim. El Roi -> God who see (Roi God/El Roi) again, not to close possibility that El Roi may simply be a different God. Yahweh -> Yahweh (He is/He causes).
The problem with thinking that El Roi might be a different God from Elohim-YHWH (and the same for Elyon, etc.) is simply that those names are used in conjunction with Elohim-YHWH to show they are the same. For example:
In Genesis 16:13 So Hagar named the Lord who spoke to her, “You are the God who sees me,” for she said, “Here I have seen one who sees me!”
The Bible specifically states that El Roi is YHWH.
I mean, duh... Translating Yahweh into Lord simply doesn't make sense.
This is an ancient tradition. It actually started in Judaism to keep from breaking the commandment "You shall not take the name of the Lord your God in vain." YHWH is the personal name of God and should never be uttered lightly. Therefore, a tradition of writing "YHWH" but reading it as "Adonai" developed. This is called Kethiv/Qere (sometimes spelled Kethib) and means "what is written" and "what is read." There are actually many such in the Hebrew Bible. YHWH/Adonai is called a perpetual kethiv/qere, meaning that only the first instance is marked and the reader is expected to know it every other time it is encountered in the text.
Hebrew was originally written without vowels. These kethiv/qeres will have the consonants of one word in the text and the vowels of another underneath it (Hebrew vowels are almost all below the consonants they pair with). The resulting word may make no sense, but if the vowels from the marked word are placed on the consonants in the margin, it will have the word the scribe wanted.
The tradition was picked up in the Septuagint in part because there simply aren't the right letters in Greek to transliterate YHWH.
Why not let the readers decide what it really means and translate the bible as faithfully as possible? Is there such translation.
You don't mean as "faithfully as possible," you mean as "literally as possible." Those are two very different things. Every Bible translation attempts to be as faithful as possible within their translation philosophy. Translated literally it becomes a mess. The purpose of translation is to render the original text so that the reader does not have to become an expert on Hebrew/Greek grammar.
There are countless idioms which do not render word-for-word into English in an immediately understandable way. Since we want English and not English-vocabulary-with-Hebrew-syntax, we don't render them word for word. For example, the Hebrew way to tell a persons age is "son of X years." Another example comes in Gen 11:1, which literally says, "And was all the earth language one and words ones." Yeah, "ones" is plural. There are reasons for that in the grammar, BUT since the reader shouldn't have to learn Hebrew to read the Bible, the translators render it singular.