122 - I don't have scarlatti
132 - I have the same answer - I think the tense is right
12 - female swimmer initials J G
114 - I also have Goethe but not 100% happy. I think Rowe is wrong as the title refers to a woman.
OK - so we have a choice of Mozart, Gluck and Scarlatti who all appear to have died in Vienna but no mention of Demetrio being lost, or Bachschmidt who died elsewhere but whose Demetrio is lost. Hmmmm!
Q114 - further to my answer. I think I read nearly the whole of the book, well skimmed through it anyway, and found proof that Lothario had a sister, Natalia, who married person in question.
Q122 - Splitting hairs here but Metastasio was a 17th-18th Century composer (Born 1698)(Question stipulates 18th Century) so that "should also rule that one out :-) I had Bachschmidt but have started having big doubts now.
Scarlatti - Wrong Century
Bachschmidt - Wrong place of Death
Mozart - right century - but Demetrio not noted as being lost
Gluck - as Mozart, although Demetrio re-named Cleonice (would this be classed as "lost")
I was obliviously happy with Bachschmidt until now :-)
Probably too late now, but i went for Metastasio, though alunrw brings up a good point re. the centuries, it matched every other critea though. The problem I had was that Metastasio wasn't the name he was born with, but then they didn't ask for that.