Preflop
Calling 54s is optimistic. Despite getting odds and a weaker player (CO) in the pot, I don't think this is an automatic call. You are deep with the CO which helps you, but maybe too deep actually, as 30/7 doesnt seem to be super terrible, so I don't think you want to stack off for 200bb with a 5-hi flush or a trips-no-kicker. I wouldn't go as far as saying preflop is a mistake, but I would recommend folding such a trashy hand.
Flop
I think donking is a clear mistake. You absolutely need to allow UT to cbet this, he will be putting in money there very often with very weak hands. So if you have a set, you surely want to check. If you have a Kx you also want to check for sure. And with a draw you should therefor check as well. Whether to check raise or check call we will see when the action get's back. But donking, even though it works out ok with this hand, is not a play you should be going for here ever.
Turn
Now that CO apparently has a piece, and you have a nut hand, you should go for maximum value. I don't think you can force a call from 66-QQ. So I think you should concentrate on his Kx, Ax and draws (65hh,55,maybe a floated QJhh). I think all those latter hands will continue to a bit bet. so betting 30 into 47 is actually a HUGE mistake. You should be betting at least 39. I actually don't think there any bet size is too big there. He is going to have KX
as well as A2,A3,A4,A5 in his range which are not folding even to a 90 dollar bet! I think I prefer betting 45 to get called by Kx still. But betting double pot is fine too. I repeat, betting 30 is way too little!
River
My general take is not to go for river check raises against fish. They will surprise you with ridiculously nitty check backs, like he might check back KT here, thinking the pot is big enough for his hand. (You have to understand fish think differently about pot. $100 is a big pot for him.) Also, if he does bet, he will often times bet very small.
Now that is not to say that check raising is always bad. Some fish are very aggressive and will bet even 77 on the river for no good reason. But in general trend towards betting yourself. 30/7 stats indicate passivity, so I would certainly bet myself.
As for sizing, I think you should target his Kx. whatever amount he will call with trips. I think betting 340, over triple pot, is a bit too much. I don't hate it, but I think the golden amount is more around 170, where he will just snap call Kx and might still call Ax.
Overall
Turn bet sizing is the biggest mistake in this hand. Simple concept: strong hands versus fish -> bet big! (Not always true of course, but here with the possible turned flushdraw it fits)