I think folding to the biggish river bet with a 4-str8 and 3-flush on board is fine. However, I like raising the turn. There's alot of draws and worse made hands that will call. Plus, it can sometimes buy you a free showdown on bad rivers like here. Also, I don't like calling the drawy flop with 2nd pair, there's alot of reverse implied odds, bluff raise or fold, preferably fold.

So, as played, i would
fold flop
raise turn
fold river