I think this will probably rehash earlier points, but here's my thoughts:
Game 1:
T5: I have no idea why you bought Trader here. If there are Fools Golds on the pile and you're trying to win the split, you should really only buy cards that give you a future advantage in buying Fool's Golds (such as Margrave or Nomad Camp.)
T6 (and several others): Spy is really not that good in general, and specifically here it doesn't synergize very well with terminal draw at all. You were afraid of a second Margrave, but dead drawing a Spy with Margrave is about as bad as dead drawing your second Margrave.
T6 (specifically): With $7 left for your remaining Buy, you had a number of good options. Gold is more valuable than you give it credit for even in a Fool's Gold game. Think about it: A hand of three Golds and a hand of three Fool's Golds have the exact same value. Even the hand of 2 Gold and 1 FG is just barely worse than a hand of 2 FG and one Gold. No shame in picking that up. Alternatively, you could grab a Margrave here. With 16 cards in your deck, collision isn't a huge concern, and the more frequent +Buy and attack make up for the occasional collision. If you collide with Trader, you can always just use your second Buy to gain a Silver instead.
T12: By now your deck has 11 Treasures (and only 5 of them worth anything, though you only get the benefit of four of them) and 23 cards total. Margrave really starts to lose value here. This is why your opponent kept buying Money; in the absence of really strong engine potential, you're going to want to sustain your money density, and just Fool's Gold isn't good enough for that. It's true that you're diluting your Fool's Golds a bit by doing this, but the Fool's Golds themselves can enable purchases of Gold (or you can use the Reaction if you have one FG and a Margrave, etc in your hand). You basically didn't commit to terminal draw hard enough. You can have a few Actions, but you can't reliably count on cantrips at all.
So basically, buy Gold and Silver over cantrips in terminal draw big money. Also, Spy's pretty bad.
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Game 2:
Overall, I think it would have been better to go for Silk Road first. To get 4 point Silk Roads, you need to get 13 more Victory cards on top of your starting 3 Estates. This is actually a lot easier than getting 30 more cards to get Gardens to 4 points, and once you saw your opponent go for Mercenary on the first shuffle, you could have seen his deck was less well equipped to contest Gardens then to contest Silk Road.
T3: I actually would have gone Gold / Copper (or with Silk Road, Gold / nothing here), for one simple reason: Gold / Copper is far better to have than Silver / Silver in the presence of discard attacks.
T5: I agree with your buy of Horse Traders on 6 here. You really want at least two as soon as you can and you didn't have many great opportunities prior. Horse Traders is a fairly soft terminal that tolerates collision well.
T7: I think I would have gained one more Horse Traders before starting the rush / slog, but clearly you had some time on your hands. Remember that in the event of terminal collision, you can still use both Reactions, and the HT is a good target for the other HT discard. You can see it's evidently clear that your opponent has no intention of contesting Gardens at this point, and even if they did there's another pile for you to get VP from, so I would have spent a little longer building. You end up buying another HT on Turn 9 anyway.
Overall I think you made mostly the right calls here - the threat of Prince Militia here makes an alt-VP strategy your most effective counter-attack. I would have just bought a few more Horse Traders, gone Silk Road first, and then Gardens to end the rush.