Everything is fair game in China: pens, swiss army knives even perfect knock offs of the Merkur Futur adjustable razor. I am not an expert in patent law but whether expired or not you cannot get judgment against Chinese makers easily though Victorinox recently won nearly 10 million damages and a recall from a company in the US marketing knock off saks. If the Parker's patent is still valid (no idea) and someone like Goulet marketed them there could be a case for litigation I guess.
I think that's the point: the owner of a US patent can sue a US manufacturer of an infringing product directly, but with a foreign manufacturer (e.g. Chinese) of an infringing product, their only recourse is to sue the importers, sellers or (possibly) users of the infringing product.
To sue a foreign manufacturer, they'd have to own a patent in the country of that manufacturer. Since applying for patents in every country in the world would be prohibitively expensive (well, even more prohibitively expensive than applying for one single patent already is ...), most will opt to file for patents in the countries where the main markets for their own products to be protected are, thereby preventing local manufacturers competing by selling infringing products.
Note that simply owning a patent doesn't prevent anybody else from doing anything they want: it merely gives the owner the right to sue for infringement. It also seems that, at least in Europe, IP rights holders can apply to have customs enforce their IP rights on imported goods (presumably by seizing the goods) - see "3.1 I hold an intellectual property (IP) right; how do I apply for protection?" at https://www.gov.uk/g...property-rights
In an idle moment in my lunchbreak, I delved into what the requirements might be to make such an application and I found this statement "Regulation (EU) No 608/2013 does not set out any criteria for ascertaining the existence of an infringement of an intellectual property right (recital 10). The question of whether an intellectual property right is infringed is a matter for substantive intellectual property law, as interpreted by the competent national courts and the Court of Justice of the European Union." - IANAL but I would imagine that might mean you need to have successfully sued in a court and received an injunction on the import of the goods, then you could apply for customs to seize the goods at the port of entry. Or it might not, who knows where lawyers are concerned?? I suspect it's easier to prove infringement when you have totally counterfeit goods posing as the real thing (with same logos, trademarks, packaging etc.), maybe less so when it's a product infringing some patent protected internal mechanism, say.
Anyway, the long and short of it is that there would probably have to be real damage inflicted to an IP protected product (financial or brand image) before it becomes worthwhile exercising IP rights through the courts. A few hundred pens with Parker or Lamy look-alike attributes being individually shipped to FPN fanatics would clearly not be worth the bother. Crate loads of fake goods like handbags, perfume, SAKs etc. being imported would be another matter.