How hard is it to find the title of a song? Harder than I thought. Attempting to find the songs and arrangements for the 1987 concert took me about 3 hours and I found 7 of 9. While not perfect, it is still amazing that I was able to comb YouTube and the Web and find samples of that many. I figured I listed to about 30 or so YouTube recordings of each and every song to confirm the title and arrangement.
Here is a bit about the process.
Let's take 4 songs from the 1997 Concert as examples.
On the surface, this one seems easy. Everyone knows Ave Maria. Except that this is not Ava Maria by Schubert. Nor any of a dozen other composers.
In researching this I eventually found this wonderful website titled "The Many-Faced Ave Maria: From Schubert to Bruckner" It seems that a song called Ava Maria was composed by Franz Schubert, Franz Liszt, Charles Gounod, Anton Bruckner, Dvorak, Verdi, Brahms, just to name a few. This site is an excellent reference.
So after listening to 10-20 songs, I have nothing. Finally I get a clue when I see some links to "Gregorian Chant" and I realize that this version is sung acapella. It may be another dead end but let's search for "Ave Maria - Gregorian Chant", and Bingo! This is not "the" arrangement, but it's close.
So just another 10-20 videos based off of this search and score! We have the song and the arrangement. Ave Maria by Tomas Luis de Victoria.
Let me simplify the thought process and what I searched for.
Sol Le Ta - nope
Soleta uni geneto - nope
unigenito latin soleta - nope, but close
just 20 videos more and Score!
Psallite unigenito, by Michael Praetorius
Or Bach, or Mozart, or etc, etc,
After an hour of listening to dozens of variations I'm going to have to give up on this one. There must be 100 songs titled Agnus Dei alone, and then I realized that it also could be a Mass. Even if I assume the first note is the key for the piece, B flat is the most common there is. All I can say at this point is that it might be a song called "Agnus Dei" or it might be a "Mass in B flat major".
Where to even start with this one?
This is me trying to guess how to spell Church Latin.
Hos po de meali
Hos po de po mealwe
Hos po di po milwi
Has po di po melwi
No surprise but no hits whatsoever.