Sometimes there are no symptoms, I had a sore throat, that's all, no cough, but it was not responding to salt water gargling or any other over the counter products, my doctor ordered a chest-xray which revealed pneumonia! treated with antibiotics. Follow-up CT.Scan (I have a smart Dr.) revealed lung tumor hidden behind pneumonia scar tissue. Surgeon removed tumor & nearby lymph nodes which contained trace of cancer in one of them. This is being followed up by chemo from which I've experienced almost no unpleasant side effects, & one good one (with two pretty wigs ~ no more 'bad hair days' for me)
Your wife may prefer the bliss of ignorance, but is it blissful? certainly not for you, nor do I suspect for her, there will always be this nagging doubt she'll have to deal with on top of everything else
Informed (first hand) advice & genuine caring support is guaraneetd on this site, but as some of the prior posts stated ~ we're none of us Dr.s
An ongoing cough, or indeed any ongoing physical discomfort is not normal, it's our bodies warning us to so something. And no amount of research ~ though you've done an excellent job I must say, is going to take the place of the diagnostic tools available to the experts in this field.
If the situation were reversed & you were the one in denial what would her advice to you be?