I'm kind of suspicious that according to the article the same factory is making 'bad' pens for China and 'good' pens for export.

I'm no expert on process improvements, but it would generally seem that once the cost to create the good pens has been spent, it would be relatively cheap to apply them to both product lines.

Which suggests either they intentionally use cheaper parts (cheaper ink?) on one line, or they have a sophisticated binning system and can identify the borderline pens and remove them from the flow going to export and instead send them to the less demanding domestic market.