I think our problem is not that we do not know Greek, but that that we do not know English as well as the KJB translators knew English.
The word “cousin” can in fact be used to mean a more general relationship. According to the Oxford International Dictionary before me, it can mean:
*Any collateral relative;
*(One’s next of kin;
*A title used formally of one monarch to another monarch;
*A person or thing having affinity of nature to another;
*A person of kindred race or nation;
*A prostitute;
*A dolt;
*A cousin once, twice, etc. removed (a) the child, grandchild, etc. of a cousin; (b) the cousin of a parent, grandparent, etc. . . .
*Kindred; related
*And more.
* * * * * * *
I think we need to study more English than Greek. The word “cousin” means, precisely as the koine Greek word, suggennes.
Our ignorance of the vastness of English is not a basis for criticism of the KJB translators.
They chose a great word, “cousin.”
Trouble is, language is not dead. It changes. Word meanings change. It is not what the word used to mean, but what it means today that matters.
People do not stop at every word in the Bible and check what it used to mean, but interpret it as it currently means. And that's where weird interpretatins begin to pop up.
The English word "cousin" originated c. 1250 AD, as ME cosin which means son of one's mother's sister, a ligature from Latin roots con+sobrinus.
I would venture to say that it's more probable it meant the same thing 400 years later, when KJV was published, then today, 758 year after its formation.
Our ignorance of the vastness of English is not a basis for criticism of the KJB translators
Perhaps the English-speakers ought to study the vastness of history in order to be able to put the vastness of the English language (which is not English in most cases, but foreign imports, often with distorted meanings) in order to match the meaning it had within the historical context of what the word meant at some particular time.
Dumping a list of everything the word meant over its entire historical existence does not provide for the correct interpretation, as you seem to suggest, by cherry-picking the meaning that appeals to the reader or reader's agenda or preconceived notions the most. (sort of like the way Protestants interpret the Bible)
I have checked several dictionaries, including Webster's, and they all place the meaning of cousin being a child of one's uncle or aunt as the most current and most common meaning.
What will an average Bible-reader, who knows nothing of koine Greek, history, and Middle Eastern cultures, most likely conclude when he or she reads that Elizabeth was Mary's "cousin?" Will the reader say "oh, they must mean kinfolk?" Of course not. The reader will interpret the word according to its current most common meaning, which is wrong.
So, while it may have been interpreted correctly in the 17th century England (which I doubt), we no longer speak that way and are not likely to interpret words according to their archaic meanings.
This is one reason why the outdated, archaic KJV is the worst possible biblical source for contemporary use. The other reason KJV ought not ot be used is simply because it's based on flawed sources.