Oh no! That's unfortunate to hear, though I must confess, despite growing up in the east US, I was unaware there was such a thing as the eastern cougar. Well, technically there wasn't I guess, since 1938 was the last sighting and I'm not that old haha.
I've also heard there used to be an eastern woods buffalo in the east US, but that its actually a myth. Do you know anything about that?
It's not that strange that you have not heard of it since it has been gone for such a long time. Even the people who are 80+ years probably don't really have any knowledge of them, since they have been very rare for the last 100 years.
No, sorry, I don't know anything about it. My knowledge of the wildlife in North-America is actually pretty limited to certain small topics that I have found very interesting ;)
Best regards from @valth