@ Karl W. Randolph
I'm glad you agree with me that the LXX's 'problem' you mentioned is, really, in common - sometimes - with other Bible texts, MT included.
So, 'a trouble shared is a trouble halved
I apologize the wrong wording of mine. Instead to write 'in any case', or, 'anyway', I wrote 'in every case'. Sorry.
"I’m not sure what you mean by this, especially by your use of 'eclectic mode'."
Perhaps my wobbly English wasn't enough correct to explain well this linguistical term. In any case (I hope I'm using this expression correctly, now!), there are two basic modes of approaching to a TaNaKh translation: 'diplomatic' and 'eclectic'. Instead to let my head to spin to the purpose of explain you these terms I prefer to indicate you a couple of references in good English: (1) A Student's Guide to Textual Criticism of the Bible
, by Paul D. Wegner (2006), sections 4.10-4.11; (2) Textual Criticism of the Hebrew Bible
, by Emanuel Tov (2012), see - on the inside of the index - the entries 'editions' > 'Hebrew Scripture' > 'diplomatic' [...] 'eclectic'. For my viewpoint, the eclectic mode is the better way to approaching to a TaNaKh translation (like I'm performing in a Genesis translation).
"Where did they get their understandings?"
From the same place you get your understanding about the concept that, like you said, "[the term 'desolation'] most likely had a different pronunciation than 'sword'", that is, Logic
. Yes, just like it is only logical to conclude that two terms linked by a common root had different pronunciations (so we can distinguish one or another derivatives), in the same manner it is only logical to conclude that two verbs which possess superimposable semantic areas, along with 2 radicals out of 3 in common, can be considered homosemantic terms.
"You haven’t shown by good evidence that they had a common meaning."
Sorry, but now I'm not quite with you. I've yet mentioned the scholarly comments of Davies and Fuerst that assign the same meaning to both roots. Now, if you don't go along with them you have every right to do so, but this doesn't mean that I haven't presented a 'demonstration'. Instead, this indicates that I have presented a 'demonstration' that you are free to agree with or not.
You mentioned also the necessity - for my part - to show a 'pattern'. I have no need to demonstrate any pattern. My purpose was to demonstrate that it was possible - in the past - that 'hheth' and 'kaph' were (sometimes) swapped each other. And for this goal, also one example - like that I cited - is fully enough (moreover, why you ask for 2 or 3 examples? Aren't 4, 5, 10, 350 examples better? Are you established a minimum amount of this kind of examples, to consider they are 'enough'?).This single example I've cited demonstrates, adequately, that a swapping of this kind was possible and that it occurred, actually
"At the same time, a perfectly good understanding of the verse can be made without changing a letter. All is needed is to consider all the possibilities available in the consonantal text."
If we may get "a perfectly good understanding of the verse can be made without changing a letter
" why readers/scholars (among them our user Steve Miller) think the stich does not 'make sense'? If we are discussing on Job 40:19 is because the B19 (or, another Bible Hebrew net-of-diacritical-points text, also) doesn't offer us enough information to give a number of us a persuasive understanding.