It gives a part of a logical reason for what they did. Not everything is explained, but it's clear that at least part of their thing is bringing back memories of what happened before the document from the Mariana trench was written. We also know that the class of '76 were being experimented on, that removes the mystery of why those things happened to them, gives us part of a reason for that. We have reason to believe that the reason nothing was heard from the Syncope Symphony after '76 was the death of several of their members. We have reason to belief that their members are probably human adjacent.
And that was after one reading, I'm pretty sure I'm going to pick up on some more stuff after another reading.
It doesn't fully explain them, but it gives us a basis of understanding that we did not have before, and while I think the article is well written enough that it has value in its own right, considering it cannon does slightly hurt the other articles in the class of '76, since things about them make some sense now. Because the complete and utter lack of logic in the actions of the Symphony was part of what made them spooky, and that is partly gone now.
I am very tired as a write this, so if I spend a lot of time repeating myself or was unclear, sorry.
I did still +1 this by the way.
Edit: of course any and all information could still be completely false, but assuming that kind of makes fiction pointless.