I don't have any problem understanding the English in the KJV. Do you?
Problem? No, not really a "problem" as though I can't understand it but that doesn't mean it doesn't sound foreign or that it isn't more difficult than it needs to be, especially when trying to read longer passages. Also, for the uninitiated, the King James can be quite difficult indeed.
The NKJV has some problems, much like other "modern" translations. Like its incorrect rendering of Acts 12:4.
The KJV has some problems, much like ANY translation. Like the fact that the entire thing is translated into 16th century English, where there's not just individual words but whole phrases that are no longer used at all and/or the usage and meaning of which have changed significantly.
Also I don't understand why you'd have a problem with something as mundane as Acts 12:4 where doctrine isn't effected. What's so wrong with it anyway....
(KJV) Acts 12:4 And when he had apprehended him, he put him in prison, and delivered him to four quaternions of soldiers to keep him; intending after Easter to bring him forth to the people.
(NKJV) Acts 12:4 So when he had arrested him, he put him in prison, and delivered him to four squads of soldiers to keep him, intending to bring him before the people after Passover.
The NKJV seems better to me! The two rendering are very nearly the same except that there was no such thing as "Easter" when Acts was written and and so the use of "Easter" was wrong from the start*, and I know intuitively what "four squads of soldiers" means but I've never heard the word "quaternions" used ever in my whole life except in this passage of the King James Bible and neither has anyone else. Even the KJV only uses that word one single time and so it was obscure even in 1611.
Regardless, at the end of the day, a passage like Acts 12:4 is trivial. No one bases any doctrine on that passage. No one does anything at all based on that passage. How about looking at something more important like in the Ten Commandments...
How many hundreds of thousands of people protest the death penalty based on that single verse? How many millions of people have seen the television footage of someone holding up a sign at these protests with the King James version of that verse plastered on it for the world to see?
Does Acts 10:13 contradict Exodus 20:13 or is one of them translated poorly? (Rhetorical question.)
So, two thing...
First, I indulged this line of thinking just to demonstrate that it can go both ways. The real fact of the matter is, however, that there isn't anything wrong with the NKJV that can hold a candle to the fact that the KJV is translated into a form of English that is no longer being used. Not only that, but, since the advent of the internet, the English language has been evolving further and further away from it at an accelerated rate to the point that you often need to literally translate a passage from the KJV into modern English for larger and larger portions of the audience to understand what is being said.
Secondly, it wasn't my intention to derail the thread with this topic and so if we want to continue we should probably move it to another thread.
Clete
*The passage is NOT referring to the ancient fully pagan version of Easter. The KJV was making reference to the Christianized version that is celebrated to this day. The KJV itself renders the Greek here as "Passover" 28 times and "Easter" only once. "Passover" is definitely the correct translation.