What you are insinuating is that the greek writers are more honest than the greek to english translators. There is not a word in the world, that I am aware of, that cannot be understood in english. It may take several words to make the trip, but it can and has been done. I would ask you to point out just one scripture concerning doctrine, in the KJV, that has been translated in such a way as to have lost the original intent.
Anyone that has ever picked up a pen can and has made errors. It is up to us to study and seek those out, and to say that we have learn greek to do so is saying that every KJV bible is erroneous. Do you really believe God would allow His word to be perverted for hundreds of years?
I don't. I believe it to be doctrinally sound.
Translational bias is a BIG issue.
But even BIGGER, is the fact that Greek is a far more complex and richer language than English, and most other modern languages. (Interesting and points to an early creation, to look at how with each generation language becomes simpler, not more complex as evolutionary theory predicts! But I digress!)
So you have all these tenses that are totally different and the verbs just cannot carry the same meaning in English. Plus a lot of words just not translated right. Nouns are a HUGE issue, because although German has four cases, they are not nearly as complex as Greek.
So a word like adelphoi, in Greek actually means "brothers and sisters" in Greek in the nominative case. That does not come through in any English translations I know of. Then there are hapax legomena. Words which only appear once in the entire Bible. Part of the method of translation, is to compare where the word is used elsewhere, if there are any questions are issues. But what are you going to do, if the word appears only once? Well, you have to look at contemporaneous texts, Greek texts written the same time the New Testament was written.
My favourite example of a very bad translation in the KJV and other Bibles which affects doctrine is "authentein" which King James' committee translated as authority, which is a completely different word in Greek "exousia". Authentein appears only once in the Bible, in 1 Tim. 2:12. Paul is talking about how to deal with a specific situation, which one can discern culturally has to do with the priestesses of Artemis coming into the congregation, and being wild, and domineering. That is the way the word is most often translated "domineering in contemporaneous sources. So you have an entire doctrine about men being authority over women, based on translating one word, and then supported by only one other verse in 1 Cor. 14, which the punctuation is a huge issues. So an entire doctrine, based on two disputed texts.
Then you have manuscript issues. Copyist mistakes figure highly in the Byzantine or so-called Majority Texts. Lower criticism (actually looking at manuscripts through the centuries) have been literally combed through and each error has a starting point, which then is recopied wrong and either becomes the dominant reading, because it has been copied wrong so many times, or it dies out, when it is such an egregrious mistake that no one can deny the copyists was wrong and entire sentences, or passages are out of place or missed or added. Mark 16:9-20 which is noted in most modern texts as being not in any of the earliest manuscripts, which means it is likely an addition, and the original was lost. To say nothing of some really bad doctrine coming out of the passage, like snake handling!
Then there are genuine and honest disagreements by scholars about how to translate a word or passage. No conspiracy, no one trying to force doctrine, just which word is best, or which way to properly word the passage to get the intent of the original writer.
So no, the KJV is not erroneous in most things, although because it is based on the later manuscripts from the Byzantine era (Because they spoke Greek, those manuscripts are in the greatest numbers) And there are many archaic words which were right and true in the 16th century, but the word is either not used anymore or has actually changed meaning. The scholars who translated did their very best, but even the original preface for the KJV 1611, states that words and meanings change, and new versions will come along.
Besides, the essential Bible doctrines of Christ, fully God and fully man, born of a virgin, lived, did miracles, was hated by the Pharisees, and crucified on the cross for our sins, and rose on the third day to show the power of God to save all people, is the same in every Bible from the Geneva to the ESV.
That is called orthodoxy. But you do need to go back to the original languages sometimes, to conclusively prove that "The Word is God," not "The Word was a god", as the JW's say, because of the nature of the Greek language. KJV and all orthodox Bibles say the same thing. But the New World Translation perverts that verse, and that is why Greek is necessary, to show these heretics why they have been led astray. And no English version shows that as well as the Greek.
God is in the business of saving and reaching people. You can be saved reading any version, because God saves us. I had a friend who was a missionary to the Jehovah's Witnesses, having been one herself for 15 years. She was able to show from a perverted NWT that Jesus was God!
So never trouble yourself, Phil, that God is going to lose his purpose in spite of cults and heretics. The Bible is the most incredible book in the world. If your preference is the KJV or the NIV, then just read it, and God will teach you and you will grow.