The same reasoning is applied to the word cherubims as to seraphims. The King James Bible is not at all in error. It should be obvious that the King James Bible is an ENGLISH translation, and to clearly show that the word “seraphims” is plural (there were more than one of them) we form the English plural by adding an “s” to the word.
There are quite a few English words whose singular form ends in 'im' and the plural of these English words ends in "ims". We have brim, claim, denim, interim, maxim, trim, pilgrim, rim and victim to name a few. The King James Bible is obviously an English translation. When an English speaker sees a transliterated Hebrew word like seraphim, we would not know if this is a singular or a plural, so the KJB translators (and many others as well) add an 's' to the end of the word to make it clear that it is plural in number; thus we have the perfectly acceptable English word seraphims.
The word “seraphims” occurs only twice in the King James Bible; both in Isaiah chapter 6 verses 2 and 3. Here we read:
“In the year that king Uzziah died I saw also the LORD sitting upon a throne, high and lifted up, and his train filled the temple. Above it stood the seraphims: each one had six wings; with twain he covered his face, and with twain he covered his feet, and with twain he did fly...6 Then flew one of the seraphims unto me, having a live coal in his hand, which he had taken with the tongs from off the altar”
We find the same thing applies when the Bible talks about the Cerubims. These heavenly beings are talked about a lot more in Scripture. They are mentioned some 59 times in the King James Bible and are found in such places as Genesis 3:24 -
“So he drove out the man; and he placed at the east of the garden of Eden Cherubims, and a flaming sword which turned every way, to keep the way of the tree of life. “
And in Exodus 25:18-19 -
“And thou shalt make two cherubims of gold, of beaten work shalt thou make them, in the two ends of the mercy seat. And make one cherub on the one end, and the other cherub on the other end: even of the mercy seat shall ye make the cherubims on the two ends thereof. “
Notice that the “cherubimS” is plural and the “cherub” is singular.
Again, the KJV rules supreme.
The Hebrew word "cherub" is transliterated in most English bibles. The plural should either be, "cherubs" (English plural) or "cherubim" (Hebrew plural). What does the KJV have? "Cherubims". There ya go... the KJV has an error (actually, 57 of them in this one example).
Case closed. Have a nice day.