It's not the gold plating that would make them look real, it would be the detail and artwork (plus weight) that I would check first.
If they had fakes that were even close to looking and feeling real, they would be flooding local coin stores and ebay. I follow this stuff fairly close and I am not seeing reports of it except for a couple old you tube videos and such. I asked a local coin dealer and he hadn't seen any increase in people trying to sell fake gold coins. He showed me a fake gold maple some employee at his store purchased a few years back and at first glance it was OK, but I could tell it was a fake once I really looked at it. He had some fake silver coins he showed me too. Nothing that looked exactly like a real coin in my opinion, but were close enough to fool someone who didn't look at them carefully.
If they ever could (and I don't believe they can at this point) come out with a really nice fake gold eagle or maple, it would really cause mayhem in the coin world because you would have to test each coin to verify it was real and that would ruin at least part of the surface. Gold has a very unique weight that can only be faked with platinum and tungsten (and keep the item the same dimensions). But everything I have read (not counting Chinese advertisements) states that tungsten is very brittle and could not withstand the pressure needed to make the coin properly (I guess it would crack?). In the old days they were making gold counterfeit coins in Europe using gold plated platinum. I would like to get one of those.
If I get back into gold, I will stick to old world/old US gold coins since I am fairly knowledgeable and can spot a fake (I think).
PS This issue is why I am getting more leary of generic silver bars/rounds. Silver is not like gold in that the weight is really nothing special and can be faked by a number of metals (some even have a ring to them, different than silver but still can fool you if not careful). I don't think there is much counterfeit silver being made now per se, but if we ever get a real rise in prices and perhaps if we stay up there for a while, there will be better counterfeits coming out because there will be more profit in it. That is why I think current year ASE rolls stashed away will be a good choice for easy sale later.
Just my opinion.
Jim