(Unless a different flag was used and it was switched, but I find that more unlikely due to quick timing.)
And as for the timing, I agree that such a quick fix is unlikely. I conflated the posts time with the time of the comment, and 15 hours seemed like plenty of time to fix it :P
While using the flag of the communist insurgents who hold the mainland for traditional Chinese is particularly egregious, the two other flags, US and German, aren't correct either, and neither is really the ROC flag for traditional Chinese. I would have just followed the recommendation not to use national flags as language icons.
I'm not even sure it's a mistake in this case. Their website says they're collaborating with a mainland Chinese institute for their process node, Hong Kong University of Science and Technology (HKUST). They might be self-censoring on the spicy Taiwan/Hong Kong stuff to maintain this working relationship.
edit: Also "LANCEVILLE TECHNOLOGY GROUP CO., LIMITED" appears to be Hong Kong-based. (That's the blue logo on their "about" page that has no information or URL).
edit2: But their Facebook page [a] just points back to LibreSilicon.com? So what is this? Is it the LibreSilicon people themselves, incorporating an entity in Hong Kong for the purpose of doing business there?
It looks like a brilliant idea(for them).