Thanks for the long answer
Imber Ranae. I just skimmed through it quickly so far, I might read it more in depth & answer later. I could just give a very short and not really satisfactory answer, considering how long you have given, which would be that I think that in those sentences in question it indeed should be rather interpreted as a copula and I would, as I thought yesterday (while I know, of course, as you stated more than few times, that esse per se doesn't have to be a copula, no problem there). But I suppose I could talk more about it after I read better everything you've written.
Anyway, thank you for your answer, I appreciate all the time you've put into this issue! Even though our discussion is not now directly pertinent to what Callaiana originally inquired (even though, in a case that it is indeed just a noun clause, it could at least influence a bit, how the sentence is/should be treated).
I at least hope that
Callaina is satisfied in that way, that the passage in question received finally some good discussion