I don't think there's going to be a lot of support for always writing aria names in the original language; if nothing else, giving the names in English early in a question allows you to obscure what language the opera was written in, which can be useful for pyramidality.
It's not the use of English names per se with which I have a problem, but rather the inconsistency. If I can expect arias to be given in English, I don't waste time trying to match them to English operas. (Just as if a tossup on
Les Miserables said some characters live on Plume Street - it obscures the setting, but if I know that that's standard, I don't immediately rack my brains for Plume Street, Cincinnati.)
There is a pretty good chance you'll confuse someone with very good knowledge if you translate aria names that are well-known in the original language, like many arias in very famous operas are.
There is also this - the fact that almost every (Western European) aria worth mentioning is better-known in the original language. (Eastern European ones are another story.)
I think writing opera questions as music questions is certainly worthwhile, but I do think you want to make sure the musical clues are meaty and memorable. I don't have huge amounts of opera knowledge, but character-signifying leitmotifs that recur after the character has been killed aren't solely confined to Tosca--are you going to make a player remember which of several leitmotifs has four chords?
For what it's worth, I would have buzzed on the second clue, because I am cautious on the buzzer and I personally don't know Wagner's oeuvre well enough to rule it out from the first clue. But the opening of
Tosca is quite recognizable. It's
difficult, to be sure, but I'm reasonably certain it's uniquely identifying.
Also, remember that even if you're not focusing on plot, that's what a lot of people know, and you do have to avoid dropping famous plot clues early (title character kills self--not uniquely identifying in opera but it does narrow it down more than one might wish at the end of the second sentence).
Suicidal title characters don't actually narrow down much of anything - comedies have already been ruled out given the previous mention of a character being killed, and loads of people commit suicide in opera - that clue (title character kills self) could also refer to Butterfly, Brunnhilde (although she does it in an opera that doesn't have her name), Magda in some editions, Suor Angelica, and Werther, to name a few really famous ones off the top of my head.
Which is slightly beside the point, as I'm not asking for a review of the question, but thank you.