Mister No
A good way to tell if an item is counterfeit is the type of box it comes in, and the smallest details that go with it.
An example here with Douglas:


Just like I have shown with my Hiro Good As New, there are some very small differences that separate counterfeit from legit (this also applies to all the Little and Big Friends releases around this time, not just Douglas.). And they are:
#1 - The box text:
On the knockoff version (top image), the “DOUGLAS” text on the bottom appears to have a more flat, budget look to it that doesn’t exactly make it seem so easily marketable, whereas the real version (bottom image) has a lot of shadows, depth, deep coloring and overall more rounded lettering than the fake. (That is something eBay sellers don’t typically notice in these types of clear-shelled boxes. So if you see that text style on the box and they listed it for cheap, snag it as quick as you can before they notice it’s a real one and not a faker.)
#2 - The stickers:
Specifically on Donald and Douglas, the stickers appear to have a slightly different and overall sloppier look to them. On the fake, the #10 is much larger than it should be on the tender and if you look very closely, the nameplate’s font is different on the knockoff, which looks like they just custom printed a sticker with “Times New Roman” on it instead of the legit font used for Douglas, and the legitimate size for his tender number.
#3 - The year of the item:
Now this specific box was introduced I wanna say around 2012, so this automatically rules out any items with the fake’s text being produced in 2012 because that’s a text style introduced a year later.
Bonus: Box types:
Now from what I’ve seen over the years of collecting, knockoff TrackMaster items tend to only have one box style, and it’s the one in the images provided. Yet as I mentioned earlier about the text…well that style was introduced alongside legitamite F-P items, however under a multitude of box types. Examples include:

(Little Friends 2013 Fearless Freddie)

(Big Friends 2013 Edward w/ detachable tender)
And to solve your suspicion…

(3-Pack Snow Clearing Emily 2013)
So to sum it up…
The knockoff company basically stole the 2013-14 text design, slapped it onto the 2012 packaging design, and reused that Thomas png (in the bottom left of the package on the fake Douglas) that was only seen up until late 2012.
Yeah, you’re Molly is very legit, your Snow Clearing Emily is very legit, and anything else that has a box with the details like the ones I explained earlier and the details in the three images above, they are 100% real.
Hope this helps despite it’s length Mr. No, great Molly vid btw! 😊