Huh?!
There are quite a few citations! Your bias is blinding you.
No no, the citations listed are citations of the claims. Not the substantiation of what the claims say. That you cite a historian from 1904 does not give us the information to confirm how the historian got that information.
Your motivated reasoning has you convinced by things that are quite unconvincing.
Regarding autumn : these festivals honor dead humans, not death of nature. “On the 17th day of the second month” of their respective calendars.
Humans are part of nature, not separate from it. "On the 17th day of the second month" applied to some examples you gave, not all (assuming the math/dating is actually correct as given, which I doubt) and one of which was a celebration in Egypt of one particular death of a God, not of mass death.
Regarding Feralia, a quick look at Wiki would've revealed that the holiday was February 21st, not 17th.
https://en.m.wikipedia.org/wiki/Feralia
That's a few examples for you.