Isn't that the definition of grey market, something built overseas and imported?
No.
I'm talking about Cat machines here. John C can comment regarding Komatsu but I suspect it will be exactly the same situation.
Some versions of common machine models were built with the intention of being sold only in a specific limited geographical market. Often (but not always) this was the case for machines built for the internal Japanese market (aka ISJ) that were never intended officially to be sold outside Japan. In the case of ISJ machines the service documentation was only ever produced in Japanese. Logical really, as that was the only location they were intended to be sold.
If such a machine then subsequently finds its way into a market other than the one for which it was originally intended to be sold then it is considered grey market. It would have been imported into that market unofficially, in other words not through any channels related to the equipment manufacturer. It most likely does not exist in the manufacturer's online service & information systems, and no service documentation or manufacturer dealer support will be available for it.
To my knowledge Caterpillar ISJ machines have turned up in the US, Canada, Australia, and other parts of Asia. Most Cat dealers, at least officially, want nothing to do with them. This is despite the fact that in many cases "crossover" documentation exists relating the grey market machine to one that does exist on the system.
Regarding your CEMA sticker. I would expect to find a sticker like that on any machine that was officially exported from Japan. I've seen plenty of them, usually on brand-new machines. Like the ones below. Both of these stickers are on officially-exported brand-new Hitachi excavators shipped from Japan to the Caribbean just over a year ago.