"it seems to me that Copper does say that his grandfather was 'embarrassed'..."

No he doesn't - see my italicization of the words 'any' and might'. Meaning, if they had felt any embarrassment, it was soon dispelled.

"I wonder which of his writings Brian could recommend for insight into his enjoyment of the musical side, something I myself sometimes think is ignored due to a focus on the words/text."

Sharp is usually criticized for the opposite failing, i.e. that he was interested only in the tunes, but although tunes were his first focus, he valued good texts too. He waxes especially lyrical about the songs he's hearing in Appalachia in letters home to his wife, but you'd need to go to the library as I did to read those. Online you could try his diaries and fair copy notebooks, which are available on the VWML site, though they take a lot of wading through, and are drier in one than the letters. The FOx Strangways / Karpeles biography has a vivid account of he gypsy singer Betsy Holland, then there's the introduction to EFSSA, and you might look at the account of Henry Larcombe's singing in 'Some Conclusions', though again that's a bit more technical than the boyish enthusiasm shown in the letters. A couple of samples below - not necessarily the best examples but the first ones I found in a quick trawl.

“I got some wonderful tunes and words this week, including a rare variant of The Cruel Mother, even more beautiful than my Somerset version.”

"I have had many long walks, doing 16 or 17 miles each day, and that very rough walking. But I am gradually getting used to it… I have got some very good songs – a wonderful version of Wraggle Taggle Gypsies much older than any I have found in England, and one called the False Knight on the road wh. I expect is one of the oldest songs I have ever collected. It is mentioned in Child who gives but one version – words only – wh. was collected in Scotland by Motherwell about 120 years ago. And now I have found another, tune and all – a great prize."

I'm preparing a piece for Musical Traditions which will go over a lot of this ground.