I just got one before they run out, and never played the game yet. Is there value to get a second box for this game to have more cards, events etc or is the base box (plus two expansions) sufficient to play with 4 or 6 players?

I'm not aware that a second core will add anything at all for this game

Yep, getting a second core is not helpful. Just play with what you have, and hope they decide to reskin this in a new setting for max compatibility