Making engines, especially complex ones, are hard, and the risk of failure goes up along with the amount of VP associate with the possibilities should you build the engine correctly (that's not to say there's always an engine on the board, that's not even necessarily true when +2 actions, + cards, and multiple gains per turn are all available. It's just usually true with the current expansions.)
Think of it like this, if you read the content here, a lot of it written by rank 60 players, they are essentially writing NBA articles about how to keep your elbow in when you shoot a 3 pointer. But you might be more like in middle school. And when you're paired against another middle schooler and he just goes for 2 pointers he's going to beat you a whole lot until you actually get the 3 pointers down.
I have kind of hit a skill plateau in that I am passing on the high complexity engines too much, and I can't afford to at my rating. A couple ratings lower if the board's only engine required you to use Trade Route for trashing and buys and Walled Village as the village and Vault was on the board, I used to be able to say, that engine is too weak, neither of us can get that going faster than Vault. But my opponents have been nailing it over and over, which requires really good balance in the sequencing and selection of the Action cards they pick up. So now I'm starting to have to try the tough engines more often to keep up. I don't actually know how to pull them off, and am pretty sure a lot of times I would be taking a higher win% not trying them and just sticking with Big Money, but I have to learn sometime. (Sometimes there's a complex and simple engine both available on the board too, also, a good example would be Alchemist stack versus a Village/Smithy type engine that's stronger)
In my opinion (not a firm one), you should put the advanced stuff on hold and enjoy the phase where people pick up Loan instead of Steward in their suboptimal engine decks and just beat them with Big Money. Because big money can lose to engines in different ways, and it's interesting and also valuable to learn the different ways why. Sometimes an attack cuts too hard at what Big Money is trying to do, and the board lets them play the attack more often than you think. Sometimes Big Money can actually beat them to 6 of the Provinces, but there's a lot of Alt VP on the board to catch up. Sometimes the Big Money strategy is a little bit faster, but not faster enough to that it can ignore Duchies and must buy them because of the Engine's pressure, but then the engine can handle the Duchies being in the deck better than BM can. Stuff like that.
