It does; the lose-track rule can apply when multiple cards are gained at once, such that you can topdeck two cards in one order but not the other. I think it's Haggler in play buying an Inn gaining a Nomad Camp, but I'm not entirely sure about it.
Things must be reacted to in the order in which they occur. This applies to all Haggler gains, actually.
1. I play Haggler. I have Watchtower in hand.
2. I buy Mountebank. [I have not yet gained Mountebank, gaining happens after buying]
Time for reactions and effects from buying Mountebank.
3. [Haggler] I gain Village.
Time for reactions and effects from gaining Village.
4. [Watchtower] I may put Village on top of my deck.
Reacting to Village is finished.
5. I gain Mountebank.
Time for reactions and effects from gaining Mountebank.
6. [Watchtower] I may put Mountebank on top of my deck.
I can't change the order, because there's no way for me to gain Mountebank first, or for me to wait until after gaining it to topdeck it.
In the case of the four Golds, you can't gain more than one thing simultaneously. Card Silly can react to any of the four Golds. Same as Watchtowering the Curse and Copper from Mountebank (just because you gain both in the same statement doesn't mean you can't react to the first before the second happens).
An easier example is:
I play Treasure Map. I gain the first Gold, which by definition goes to my discard. I activate Watchtower to trash it, and choose to apply Watchtower's effect before Treasure Map's. Watchtower trashes it. Treasure Map tries to put it on top of my deck, but it can't because it expects to find it in the discard, not the trash.
Then I gain the second Gold. I activate Watchtower to trash it, but choose to apply Treasure Map's effect before Watchtower's. Treasure Map puts it on top of my deck. Watchtower tries to trash it, but it can't because it expects to find it in the discard pile, not the top of the deck.