There are federal penalties for labeling a product as "made in USA" if it isn't. I doubt that Nicholson would mislabel their product. however, it doesn't preclude a counterfeiter from mislabeling a product.
My Nicholson files are all more than 30 years old with some going back fifty years. There are multiple variations on the trademarks depending upon when they were purchased and what style of file it is.
Whereas I used to be able to find Nicholson files at the local farm supply or DIY, they are no longer sold there. Whih is largely why I haven't bought a Nicholson file in the past several decades.