Name one concept from Greek or Hebrew that can't be expressed in English or any other language.
How about verbal aspect? We simply do not have anything like it in English. The Aorist tense, for example, is normally translated as past tense in English, and 85% of the time, it is! But the other 15% of the time it is present or future. This is because Aorist is about the whole picture, as seen from outside, rather than tense being the most important thing.
In Greek, verbal aspect is more important than tense. How the writer views things, from the outside, requiring a perfective aspect like the Aorist, or an imperfective aspect, like the present, which recalls events from the inside. Time takes a back seat to aspect, resulting in English not capturing the nuances of this important fact.
It's also the reason a verb can be in the present tense, but translated into past tense in English. The historical present is used with verbs of saying and motion, and English can never capture thus imperfective aspect of the historical present.
As for Hebrew, the entire verbal system, which is the most important part of the language is different than English. We don't have Qal, Nifal, or Hithpael. I won't even get into it, here! Hebrew is also a very black and white language, and it is hard to carry that into English.
There are just so many wrong things on this thread, especially by the OP. For instance, doeps Pete know that the science of lower text criticism is very advanced. Every manuscript from the Rylands papyrus of John, dating to the 2nd century to the much later Byzantine texts, have beeen scrutinized, mapped charted and cross referenced.
The result is that it is easy to trace manuscripts and their mistakes. So a copyist error in the 5th century might be carried down through the centuries in the copies of the copies of the copies. Byzantine manuscripts from which the KJV was translated, are actually the majority texts, and of the poorest quality. Because Greece and Constantinople kept its Greek, scribes continued to make copies. Sometimes scribes would add a notation in the margin. Often, these notations can be found on the first copy where this was added. Then the next generation of manuscripts, that margin notation would be added into the text, then repeatedly copied. This is a big issue with making simple statements about Jesus, into high Christiology. So for example, the earlier documents might say "Jesus" in a verse. In the 8th century, a scribe would add, "the Lord Jesus." In the 11th century a further scribe might add, "the Lord Jesus Christ." That is high Christology! And it is added. Of course, it is a true statement, but it is often not their in the earliest manuscripts, because it was added by copyists.
Finally, the KJV was translated using 7 very late, corrupted manuscripts, which is why there are so many added verses. Erasmus, a Catholic priest translated them and the Catholic Church made him keep spurious verses to support RCC doctrine, even though the verses were obviously added. Older manuscripts are always better, because they have not welcome corrupted, like a game of telephone! But, they all need to be compared and translated with wisdom.
I hope one day we discover some of the original autographs. There are libraries in Greece and Istanbul, which have millennia of Greek manuscripts. Daniel Wallace is photographing all of them and cataloging them. Who knows what he will find?