Moshe > I do question whether Oct 7 events qualifiy but as I heard on one program, all bad events that occur to klal Yisroel stem from the destruction of the Batei Mikdash,
This is separate from the music. I heard it from multiple Rabbis that all tragic events are included, especially for a specific community. I am not sure it has to be necessarily linked as “stem from”, although it might be. Commemoration is a straight-forward issue not requiring theological justifications, I think.
I am a little surprised that when you were listening about Oct 7 events, your thoughts go to “do they qualify”